Izumi Koushirou: Koushirou is the computer genius of the Chosen Children. His skills with his pineapple laptop are unparalleled. However, he lacks social skills, why is that? The boy has very little human contact, he only has a handful of friends. This is very strange he seems like a normal kid, he acts quite normal around his friends, but he acts very odd around others. This unusual behavior is a result of his family and his society.
Near the end of the Vamdemon arc, we find out that Koushirou was adopted. His biological parents passed away when he was very young (my guess being around 1-2 years old). Since Koushirou's parents had no living relatives or family who were close (personally, not location), a very distant relative* took the orphaned child. They had recently lost a boy of their own to Shinigami, so they were grateful to have a second chance to raise a child.
As the years went by, Koushirou grew up and never knew that the woman he calls "Okaa-san" and the man known to him as "Otou-san" aren't the ones who gave him life. His "mother" wanted to tell him the truth, but his father wanted to wait until he was older. Either way, the news would have come as a shock to Koushirou. Adoption isn't very popular in Japan, it's believed that it ruins the family's bloodline. It gives a child a family's name without having any of the family's blood. Its part of Japanese pride of heritage. Izumi-san (the father) wanted to wait to tell Koushirou because Western influences are beginning to change Japan's cultural views, a modernization of tradition. Koushirou is of the generation that will be greatest effected by these changes; his father hoped that his adoption wouldn't matter too much because the Western influence on his son.
However, Koushirou's mother won out in the arguement, to some degree. Unknown to them, on the night they were discussing the plan of action, Chibi-Koushirou snuck out of his bedroom to get a glass of water. He overheard the whole conversation. Sadly, what Izumi-san feared would happen if they told him now, happened. Koushirou was devastated, destroyed and even traumatized. The people he calls "Mother" and "Father" aren't really his parents. After this moment, Koushirou begins to hate himself. He feels like he has stolen the Izumi name and contaminated the Izumi bloodline.
At this point, the child searches to find a way to forget about his shame. In his eyes, "Izumi Koushirou" is now a fraud, nothing more than garbage thrown off to the side. Feeling like he is undeserving of human companionship, he focuses his life on his computer. This is to escape the reality he lives in, so he doesn't have to deal with the shame. If he stays away from everyone, no one will know his disgraceful secret and no one will shun him. Through his computer, Koushirou is reborn, separated from his old, cowardly, disgusting life*. However, he will eventually find himself some genuine friends: the Yagami siblings, Taichi and Hikari, and Takenouchi Sora. Koushirou becomes very attached to these three (he feels like nobody would like him) and they somewhat keep him normal.
Because they are so close to him, Koushirou always speaks to his friends with respect. He always calls them Taichi-san, Sora-san, and Hikari-san, a rather respectful tone for a ten year old to use with his friends. This tone also flowed into his normal speech. Since he feels like he is the scum of the earth, he treats everyone like they are better than him (he calls everybody "****-san"). However, other than his three friends, he doesn't know how to interact with people. Throughout the series, he always sided with Taichi and Sora, and tended to follow in their shadows. When they were all seperated by Devimon, Koushirou found himself alone again. Without his friends with him, he sinks back into computer world. This is why Mimi becomes enraged when he showed more interest in his computer than her. He even mentioned to Tentomon that he doesn't really long for human companionship and is happy by himself. This is still his resentment towards himself speaking, he feels like he doesn't deserve to be with others.
As the final battle with Vamdemon approached, Koushirou confronted his parents about his adoption. There he learns that they took him in because they wanted to, they wanted give him the life that his biological parents are unable to give him. Koushirou realizes that his parents love him and don't think of him as a poison to their family name; they never cared about that. As far as they were concerned, he was their real son. With this burden off his shoulders, Koushirou is able to dream of things besides a new life, but most importantly, he can enter society with honor.
*It isn't exactly said how distant they are. I would assume that Izumi-san is a second or third cousin, or a half-cousin, of Koushirou's father (The relation could be through the mothers, this is just an example.). I assume the family interaction is mostly holiday based, like the relative you almost never see, but send a Christmas card to every year. This generation distance would mean that there is very little Izumi blood left in that side of the family.
Tachikawa Mimi: Mimi's dominant trait, like the other season 1 chosen, is embodied in her crest: Purity. When watching the Japanese version of this show, Mimi's personality is dominated by it. Mimi (and Joe) has possibly the most realistic reaction to the Digital World of all the children. Unlike most of the others, who are only mildly surprised by their sudden appearance in a foreign world (a trait common to anime characters in general, so don't fault them), Mimi is terrified of the unpleasant world, and is not afraid to state it. In some ways, her purity can have the same meaning as the dub's sincerity: Mimi is quite blunt with what's on her mind, without realizing how it might affect those around her. She, along with Takeru, are the only ones in the beginning of the season who are considered to be 'kids'. It is possible that the others use Mimi and Takeru's innocence and naivete as a measure to keep themselves calm. As a result, Mimi is babied somewhat.
But this is not the only instance of it for her. Mimi's life has been nothing good treatment and happy moments. In short: Mimi is sheltered. The Tachikawa family obviously puts a high priority on happiness over anything else, as a result, Mimi has never seen life for what it can be: harsh, cruel, and certainly unforgiving. Additionally, she is the only child of the family and has never had to develop an intimate relationship with anyone. This puts Mimi in a position where she is unable to act appropriately with others. The worst part about this scenario is that Mimi is naive to the fact that she is acting inappropriately. It becomes a shock when she is suddenly forced into a position where she has to take responsibility for her actions, and quite possibly she might have died on many occasions if she was not fortunate enough to always have Palmon to look after her.
Mimi's parents are a happy family, unlike many of the other children. In fact, they are quite wrapped up in eachother. This leads to problems in Mimi's life, too. With her parents so wrapped up in each other, where do they find time for Mimi? This goes back to the idea that Mimi is a sheltered child. With as rich as their family seems, it's quite possible that Mimi's parents just buy her happiness. And with all that spare time, I would think Mimi would be deeper than she seems, maybe she's an avid reader. (you never know ^_~ the series doesn't say she ISN'T!)
On a positive note, her innocence is also her strongest quality. Just like Daisuke's open nature, Mimi readily accepts friendship, and is quick to forgive, and LEARNS to be quick to apologize. Her first major life lesson comes from guilt, an emotion she is completely unnaccostumed to because she has never done anything intentionally wrong before. When she locks up Taichi, Joe, and Palmon in the Gekomons' dungeon, she is panged with an emotion she doesn't understand (which Sora helpfully explains is guilt). Finally understanding, she quickly apologizes, and she is easily forgiven as the others understand that the wrong was committed unknowingly.
After this initial moment, Mimi begins to mature, she realizes that she has a responsibility, and that she must learn how to act to fulfill that responsibility. She never loses her innocent way of thinking, however. She tries to provide support for her friends as best she can, and eventually, her desire to protect her family (who for so long protected her from everything) was the point in which her purity was strongest.
Mimi was far from matured, however. With her newfound desire to protect her loved ones, came the understanding that all things that live deserve to be protected. She really wants to help out the other children. But, this is not something an inexperienced, sheltered girl should do. It causes major problems to Mimi's psyche to watch friends die and disappear in front of her. After one too many battles, Mimi completely loses it and refuses to fight, scared that one of her friends might be hurt for some senseless reason. She even leaves the group to get away from the fighting, but to help out in her own way. She found herself unable to cause pain to ANY living thing, even those which threatened her life, such as Ogremon and MetalEtemon, the later of which caused the death of Leomon as he tried to protect her. It wasn't until Joe explained to her that having friends meant making sacrifices for them, that she became able to fight for those close to her once again, though she was still a bit reluctant and would continue to try and find alternatives before fighting the rest of her life.
In summary, Mimi was raised in a sheltered environment, unable to socialize with others (such as when she and Koushirou are trapped together in the labyrinth in episode 10) or cope with the dangers of the world outside her bedroom, such as the deaths of Piccolomon and Chuumon. Through the help of her friends and with some self-discovery (when she felt guilt for the first time), she realizes that she must learn how to act to not only fit in, but to keep her friends and loved ones safe. She overcomes her naivete to become an understanding and sympathetic individual with a desire for peace.
With her move to America in season 2, very little is known about her older self except that she still keeps in close contact with the other children and has made a host of new friends in America. (Personal opinion: It seems like they were just trying to open up possibilities for a third season by putting a popular character in America and then surrounding her with more Chosen Children: Michael, Wallace, the other INT'L CCs). In short, 02 Mimi is the same as Mimi at the end of season 1.
Ishida Yamato: Yamato is a cold, uncaring, lone wolf. However, this is only when his brother Takeru isn't around. If Takeru is present, Yamato transforms into an overprotective, obssessive elder brother. Notice how cold he is normally and how obsessive he is when he is with Takeru. Yamato will stick to him like glue, never letting him out of his sight. In episode 3, Yamato wouldn't even let Takeru eat a fish unless Takeru had let him deboned first. Later in that same episode, Yamato makes Gabumon sleep next to Takeru to keep him warm. Sadly, this unhealthy obsession with his brother often clouds Yamato's judgment, as demonstrated in episode 9, Clash! The Freezing Digimon. In this episode Yamato is consumed by his desire to protect his brother that he almost kills himself twice, luckily Gabumon and Taichi were there to prevent that,
Yamato: Takeru! Answer me! Where are you? Takeru-- *coughs*
Gabumon: Yamato!
Yamato: Takeru!
Gabumon: Yamato!
Yamato: *coughs*
Gabumon: Yamato, there's a cave. Let's rest a bit.
(They head to the cave)
Yamato: Takeru!!
Gabumon: Listen, Yamato, you have a cold, let's stay here and rest until the snowstorm's over.
Yamato: No, I'm all right. You stay here and rest. *coughs*
Gabumon: You're not going!
Yamato: Let me go, I have to find him!
Gabumon: Then I'll go!
Yamato: What?!
Gabumon: Listen, Yamato. I'm going to look for Takeru alone, and you're staying here to rest.
Yamato: Gabumon....
Gabumon: Ah, don't worry about me, I have a thick fur! *confident laughter*
Gabumon: Stay here and wait for me. Don't go anywhere!
Yamato: Gabumon....! *coughs*
Yamato: TAKERU!!
Yamato would have kept on searching until he froze to death. Later, Yamato attacks Taichi because Taichi didn't agree with his idea that they should begin searching for the others. When Taichi wanted to assess the situation first, Yamato went over the edge and lashed out at Taichi.
Taichi: So, what do we do now?
Yamato: We'll find the others. There's nothing else to do.
Taichi: I'm just asking, how are we going to find them? We all got separated and ended up on different islands.
Yamato: I'll swim if I must.
Taichi: Idiot! You're in the Antarctic. You'll die in a minute in that icy water.
Yamato: We can build a raft. We'll chop trees from the forest.
Taichi: Calm down now, Yamato! Even though we're separated, they'll be fine. I'm sure they will. Shouldn't we find out where we are first?
Yamato: First?
Taichi: I think this island is moving towards that world that Devimon was talking about.
Yamato: What do you mean, "first"??
Taichi: W-what?! Stop it!!
Yamato: First we'll find the others, that's what's most important! The world beyond the ocean... get lost in that world alone if you want to!! I want to find Takeru first! I'll find the others first!
(Yamato runs off and Taichi chases after him)
Taichi: Yamato!
(Tackles Yamato)
Taichi: Yamato, wait!! When we get there, we might find a way to help the others. Don't you agree?
Yamato: You can never understand how I feel!
(Yamato slugs Taichi in the face, and the infamous "bitchfight" begins)
Gabumon: Yamato!
Agumon: Taichi!
Yamato: You're heartless! I hate it when you don't care about the others!
(Taichi reverses the hold so Yamato is on the ground and hits him)
Taichi: You're inconsiderate and stupid!
(Yamato reverses the hold and hits Taichi. This goes on for little longer)
The two continue to fight until they roll down a hill. When they land on the edge of a cliff, Taichi is able to get the upperhand and is about to land the proverbial deathblow when Yamato makes his last speach. As he talks, tears are flowing down the boy's face. This is the first emotional breakdown Yamato has.
(Raises his fist for the final blow)
Taichi: You....!!
Yamato: Takeru...! Takeru..... he can't make it by himself!
Taichi: Yamato... you.....
(At that point the cliff beaks away and the two fall onto Yukidarumon.)
Later, during the Pinochimon saga, Yamato's obsession rears it's head again when Takeru is taken hostage by Pinocchimon. Yamato could only watch as Takeru was abducted (Yamato was bound and gagged at the time). Feelings of uselessness and failure begin to develop in his mind after that even. Yamato failed to protect his little brother. When Takeru proved he was fine on his own, Yamato didn't handle it so well. His world collapsed, which allowed Jureimon to manipulate him. When Takeru is forced to grow up faster than he normally would have, Yamato was unable to cope. This scarred child felt like he lost his only purpose in life, to take care of his brother. What good is brother that isn't needed? Struggling to find an answer, Yamato begins to vent his sorrow onto the rest of the CC. He believed that if they weren't around to make Takeru independant, Takeru would always need to his elder brother to help him. After he attacked the CC and realized his unhealthy behavior, Yamato went to do some soul searching, to find the meaning of his life.
The reason for Yamato's behavior is obvious, his parents' divorce. His mother, Natsuko, gained custody of Takeru, and then moved away to Shibuya. While you could easily take a train from Odaiba to Shibuya*, it's more of a matter of convenience. Yamato is no longer able to see Takeru everyday. This is what causes him to cling to his little brother, the fear of losing him. Yamato has focused his life purely on Takeru and nothing else (which leads to his cold, uncaring personality). The divorce of his parents forced Yamato to cherish what little time the two had together. This is why Yamato followed Takeru like a puppy, to maximize the time they spent together at summer camp. However, the irony is that an elder brother is always needed, for one reason or another. No matter how old they get, Takeru will always look up to him. Sadly, Yamato doesn't realize this until the end of the series
* They are all districts of Tokyo (Odaiba, Shibuya, Shinjuku, Matsumoto, etc. Almost every city mentioned in Digimon), they mainly serve as residential areas while everyone commutes to Tokyo to work. For this reason, public transportation is insanely efficient. I think we have all heard of the part of the public transportation bureau who's job is to cram as many people as possible into subway cars. That is how crowded things can get at times.
Takaishi Takeru: All of Takeru's problems appear in 02, so I'm not going into them, just as how I'm not explaining Joe's family problem (the doctor-thing appears in 02). All I will say is that they stem form his parents' divorce.
Kido Joe: Aside from the pressure to become a doctor, like Kido family tradition, Joe suffers from low self-esteem. He feels that because he is the oldest of the group, he is responsible for their well being. However, he lacks the confidence to assert his authority given to him by his seniority.
The Kido family has had a long history of becoming doctors. Two of the three Kido children have chosen their careers. Seeing as how Shin and Shuu have not become doctors, this leaves Joe to carry the tradition. However, Joe doesn't truely want to become a doctor. He is struggling and cramming for the school exams to get into a med-school all for family tradition. In one of the 02 Drama CD's, there was a scene in the Kido household. It was a family dinner, the conversation was about Joe's choice of career. The father tells Jou that Shin and Shuu chose their own careers, and that he can choose his own too. If I remember correctly, we never get to hear Joe's response, the meal was interupted by Jun ringing the door-bell. However, seeing as how Joe has worked so hard to continue the Kido family tradition, I assume Joe would still try to become a doctor. Joe is caught between his own desires and his family's history. However, seeing as how we know what happens to Joe in the end, we can say that he chose tradition, and that he was very lucky. Quite often the pressure to succeed in life is to great for students and they end up killing themselves. Suicide is rather high in Japan, compared to its other crime rates (which are very low compared to America). Joe could have easily been consumed by the stress of all his tests. Even though we have seen him very stressed out over his tests, he was able rationalize the situation and continue his studies.
Takenouchi Sora: Sora is a motherly figure to the kids, she is very serious about keeping the group together and safe. This often leads people to believe she doesn't know how to have fun, which is true to an extent, for during their stay in the digital world, she is the one person who is constantly calm and able. She is a vital member of the group in the sense of peace maker and consoling friend.
This aside, Sora is actually a fairly normal, happy prepubescent tomboy. She plays soccer and enjoys the company of her friends. In fact, she relies on her friends to keep her stable. Throughout the course of the adventure, Sora devotes all of her time to her friends. If she isn't doing something to help the others, she quickly becomes depressed and unhappy, feeling guilty for not doing more for the people she cares about. Even as such, it is apparent that Sora bottles up most of her feelings, leading to a complete emotional breakdown near the end of the stay in the Digital world. Sora is worried she has not taken on enough responsibility for the other children, and feels inadequate, as if she hasn't lived up to her crest. These feelings of worry are preyed upon by Apocalymon's darkness and manifests itself in a dark ocean (possibly the same one from season 2)which she is drowning in. Yamato and Jyou eventually convince her that she doesn't have to take the responsibility of the world, that just caring for her friends is enough to prove her love. This said, she is able to pull herself together long enough to defeat the darkness.
This over-protective nature and feelings of inadequacy could come from a strained relationship with her mother. She and her mother have a conflicting viewpoint of how Sora should live her life. As a result, they have developed a tenuous relationship. Sora's mother is constantly worried about her, and this worry comes off as strictness. Sora rebels against this and has an innate hostility for the woman. With her father absent most of the time due to his work, Sora learns to rely on herself and feels she is capable of much more than her mother sees for her. This rebellious attitude leads Sora to believe her mother doesn't love her. Such a feeling causes Sora to feel she cannot depend upon others, and she wants everyone to be able to depend on her, unlike how she feels she cannot depend upon her mother.
After seeing a parallel between herself and her mother when she tries to stop Piyomon from attacking Vamdemon, Sora realizes her mother DOES love her, but the damage is done: While Sora is a very loving person, she herself doesn't understand her own feelings.
(This may seem couples-slanted, but it's actually all based on scenes shown in continuity - movie 2 and season 2 christmas episode) Sora has a problem dealing with love. Her emotions fluctuate and she can be upset very easily by the person she has feelings for. In movie 2, Taichi tries to compliment her, but Sora's feelings for him at the time scare her and she gets angry as a defense mechanism. Later, when she receives Taichi's email with the heart icon in it, she is pleased, but never lets Taichi know what she feels. This is proven in Season 2 where she reveals to Taichi that she now has strong feelings for Yamato. Taichi is very upset at first, and she can't bring herself to console him - which is completely opposite to her protective nature. This recoil from the person she used to love shows how clumsy she is when it comes to her own feelings. We are never shown much of her relationship with Yamato, so I will not go into the potential problems and psychological causes of it.
Yagami Taichi: Taichi is very narrow minded. Not in judgement, but in his actions. All of his actions are guided by either his own personal security, or his sister Hikari. This mode of function gives Taichi two personalities: the "selfish" leader, and the obsessive elder brother. These two thinking styles are governed by Hikari's prescence. When she isn't around, we see the Taichi that we are most familiar with.
When his sister isn't around Taichi is the strong leader who guides the CC. When I said this Taichi is selfish, I mean he always has a hidden agenda. While Taichi makes choices for the good of the group, they all can be traced back to his own satisfaction. Taichi's actions are actually meant to comfort himself, to sooth his insecurities. For example, when Nanomon kidnaps Sora in episode 19, Taichi rushes to the rescue. However, he doesn't do so just to rescue his childhood friend. The secret agenda is to heal the wounds to his pride. He just stood there, trembling with terror as Sora was taken away. This is a blow to his courage more than anything else. Taichi had failed his crest, the Crest of Courage. This is why he sets out alone to save Sora, to redeem himself for his failure, and regain his courage. He even says so himself in episode 20 when Taichi and Agumon find Nanomon's laboratory,
"Taichi: We have to get to the other side.
Agumon: I’ll go first, Taichi.
Taichi: Don’t, Agumon!
Agumon: Taichi?
Taichi: I’ll go first. Behind this wall there’s something that’s very important to me.
Agumon: Sora?
Taichi: Yes, but that’s not all. There’s something more. Something very important that I lost."
This very important thing is his courage. He was more concerned with comforting himself. This urge to always succeed is stemed from his childhood, when he first tasted failure. He took Hikari out to play when she was sick. She caught phemonia and almost died. Taichi failed as an elder brother, he was supposed to take care of his little sister, but instead, he almost killed her. Since that day, he is terrified of failing at anything.
Which leads us to the other Taichi, the obsessive Onii-chan. Ironic how Taichi repremands Yamato for obsessing over his little brother, when Taichi is no better with his little sister. Ever since the day he almost killed her, Taichi has refused to let go of Hikari. This is how he is trying to redeem himself as a brother, by never letting anything bad happen to Hikari again. Aside from failing her again, Taichi's other greatest fear is that Hikari no longer loves him. It's not in her nature to say anything rude or mean, especially to her brother, so Taichi doesn't know how she feels about him. She actually blamed herself for the accident that almost killed her. Fearing that she secretly harbors hatred towards him, Taichi does everything he can to make her happy. When Hikari is present, the value of Taichi's life is controlled by her pleasure. If she is sad or hurt, Taichi feels like a terrible brother and loses his will to live.
When Hikari falls ill during the campaign against Mugen Dramon, Taichi is forced to relive the accident that ruined his sanity. However, this time there isn't an emergency medical service to call for help. Taichi beings to crack under the pressure as his two minds begin to clash. His choices became very rushed and pressured, luckily Koushirou was there to prevent him from getting himself killed. When the two take refuge in an abandoned church, Taichi confesses his crime to Koushirou. At that point Taichi does something we don't see to often, cry. This is the first mental breakdown we see Taichi have. Later, when Mugen Dramon collapsed the roads and plunged the CC into the sewers, panic begins to set in. Once again, Taichi has failed to protect his little sister. he falls into an aggressive form of depression. Aggressive meaning that Taichi will attack anyone who tells him anything contrary to what he thinks. In this case, Taichi feels like a terrible brother and hates himself. Koushirou makes the mistake of telling him otherwise, and suffers a beating from his friend. This is a sibling complex at its worst. Yamato attacked Taichi because he was saying that finding Takeru and the others wasn't the most important objective (episode 09). That is a good reason, Taichi, on the other hand, has no right to raise a fist towards Koushirou. All Koushirou did was try to reasure Taichi, he only said that Hikari is safe. Taichi feels like he is the only one who can protect Hikari, and he failed to do so.
It's amazing how only one mistake can ruin a child's mind. Because of his carelessness, Hikari almost died. For that crime, Taichi is punishing himself for the rest of his life. The sad part is that the origin of his suffering doesn't even realized what is going on. Hikari is completely unaware of her brother's anguish. All she sees is a perfect brother who she couldn't love more than anything else.
Yagami Hikari: Hikari has a very good relationship with her brother. The two have to share a lot with each other, even a bedroom. This is why the siblings are so close. However, this close relationship has given Hikari a sibling complex. She loves her brother too much; not to the point of incest, but to the point where it warps her view of reality. Hikari can't see any faults in Taichi. The child will also never speak a rude word about him, anything she says about her brother are words of praise. Episode 21 is a good example, when she is talking to Koromon after he "loses control" on the dining table:
(sounds of flatuence and an image of roses opening)
Koromon: I'm sorry, Taichi.
Koromon: I'm sorry, Hikari. I'm so embarrassed and ashamed.
Hikari: I know.
Koromon: Why?
Hikari: I used to wet my bed. Onii-chan was nice to me. He washed my pajamas in the middle of the night. Plus he told my mom about it.
Koromon: Eh?
Hikari: He's a good brother, isn't he?
Koromon: Yes.
Notice how she adds in the comment praising her brother. The point of the conversation was to console Koromon by speaking from her own "control problem " experiences. She could have left it off at where she said that she used to wet the bed. Instead, Hikari discreetly changed the subject into how good a brother Taichi is. It seems like she had an extra objective; to announce to Koromon how great of a brother Taichi is.
Hikari also doesn't like being a burden for her beloved Onii-chan. Quite often this proves to be a hazard to her own well being. When she was 5 (Taichi would be 8), Taichi took her out to play soccer when she was sick. Hikari didn't want to force Taichi to stay home and watch her, so she never protested. Eventually, she relapsed and caught phneumonia; she almost perished. On the day of her release from the hospital, Taichi was waiting for her to come home. He was expecting her to say that she hated him and never wanted to speak to him again. However, she instead appologized to him for getting him in trouble. She said she would understand if he never wanted to play with her again. The girl's view on reality is grossly warped by her love for her brother, she can't see that it was her brother's fault. After Pinocchimon is killed, the CC set out to kill Mugen Dramon. As they advance towards his domain, Hikari falls ill. However, she doesn't want to worry her brother and keeps her condition a secret. Just like last time, she suddenly collapses and scares everyone. She only wants to keep her brother happy, but she only ends up making him worry. It's a very ironic situation, Taichi is scared that his sister hates him, when in actuality, Hikari she loves her Onii-chan too much.