T. HAMADA, PERSONALITY
Patient, kind, selfless, responsible, optimistic, devoted... Tadashi is all of this and more.
Patience is one of Tadashi's leading characteristics, followed closely by a kind and caring heart. He had to grow up quickly to fill the hole left by his parents, but Tadashi's natural affinity for seeing the good in people allowed him to lovingly guide his baby brother through the jagged obstacle course of problems left in the wake of the accident. His Aunt Cass has long admitted that she doesn't know much about children, so it always fell to Tadashi to notice if Hiro was bullied at school and to step in to make sure his brother would be okay. Because he grew up quickly, he has a calm and serious side that seems beyond his years. He's tapped into that aspect of his personality along with his intelligence to go far as a student as SFIT, working tirelessly to create a robot that could save lives.
More importantly than simply being patient and kind, Tadashi is a seriously selfless person. An extreme example is how he ran into a burning building, regardless of his own safety, to try to save his professor. He's more than just extreme heroics, though. Tadashi's dreams revolve around helping other people despite any detriments to himself. He really is happy as long as other people are happy. Right after the accident that killed his parents, Tadashi began inventing goofy little toys to cheer up his aunt when he saw the pain she was in. Tadashi has always been that kind of boy – even when dealing with his own grief, his priority was to alleviate the pain of others. Almost everything he does, he does for other people. When Hiro began to be bullied at school, Tadashi built a bucket of rust and bolts that could only loosely be identified as a "ship," tacked on some thrusters, and dragged his baby brother along for the test drive. It took a serious investment of time and a risk of getting into trouble to do that, but it had the intended effect of cheering up Hiro and getting Hiro interested in inventing, which was all Tadashi could hope for.
On top of his selflessness, Tadashi is a driven man. He has goals and he works tirelessly to achieve them. He isn't one to give up at the first sign of trouble, and always tries to find just the right angle to see through his problems. Despite dozens upon dozens of failures with his robotics project, Tadashi always continued. Exhausted, but never defeated. He nurtures the same attitude in others, always encouraging his fellow classmates (and especially Hiro) to reach their full potential. Seeing his brother waste his talents on illegal botfighting, Tadashi drove Hiro to his school to see how much more he could do with his intellect if challenged. Tadashi relies more on gently nudging people in the right direction rather than attempting to redirect them with brute force. Tadashi is basically everyone's perfect big brother. He's willing to do anything and everything to help other people, displaying a level of selflessness that few can match.
Tadashi is also, let's face it, a bit of a nerd. He reads medical journals for fun, enjoys geeking out over new breakthroughs in science that he hears about, and sometimes has trouble keeping a lid on his emotions and maintaining his cool big brother status when he gets too excited about something. Nerding out aside, though, his life does not revolve around a computer screen. Tadashi is all about practical applications and pushing boundaries. Though he's graduated to less dangerous experiments compared to when he built the "ship" for Hiro's sake, he's still all about actually doing something. He doesn't want to just study ways to help people, he wants to actually be the one creating the helpful inventions or the one going out and offering assistance. Someone has to help, and he believes that he is that someone. Tadashi is not a man to do anything halfheartedly.
On another note, his baby brother didn't receive all of the family sass, either. Tadashi exudes dry humor when the need arises. He enjoys a good joke and actually likes listening to crazy stories. Since Hiro is the more excitable of the two of them, Tadashi often relies on his dry observations to shock his baby brother out of his melodramatic declarations long enough to have an actual conversation. A notable example was when Hiro gloomily claimed that he had no ideas and Tadashi responded with a dry, "Wow, washed up at fourteen. So sad," before trying to help Hiro through his block. After his brother's presentation, Tadashi broke the serious atmosphere for a moment to tease Hiro about how, instead of saying how proud of himself he should be, he only asked for a moment to talk to tell Hiro his fly had been down for the entire show. He usually uses his humor to make a point or to put others at ease.
Overall, Tadashi is basically just a good guy. He has his flaws, of course. His patience can break and he can be harsher than he means to be. After saving Hiro from his botfighting fiasco, he was angry enough to let out his frustrations on the younger boy. That sort of thing is a rare occurrence, though – most of the people he cares about don't make it a habit to put their lives in needless danger. The easiest of Tadashi's buttons to push revolve around needless recklessness or not treating other people with respect. He works so hard to help other people, that the idea of someone intentionally harming someone else or not caring enough to help a fellow human being can set off a fuse in him that normally does not exist. Despite his flaws, Tadashi always strives to be better than he was before and to help those around him improve, too. He has an eye to the future and he's excited about what possibilities it will hold. Tadashi will never stop being optimistic and seeing the best in humanity.