This is a Succession essay. I genuinely think that most characters in television and films tend to be autistic/autistic coded, and I think this is by complete and total accident
Trying to make a character weird, or giving them issues picking up social cues, or what have you, say, extremely strong interests, it often speaks to autistic people and our experiences in a variety of ways
Kendall Roy is a big one for me, he stims in his car (episode one, rapping and hitting the chair in front of him in the car before his big day?), he's so genuine and cannot tell when everyone around him is making fun of him (L to the OG, singing a rap song he made up about his dad?), he gets emotionally and physically overwhelmed (too much birthday?), he has issues expressing his emotions and picking up social cues (his phone call with the bank, telling Polk to fuck off, where he tries to emulate his father and fails?)
There's this poignant scene where Kendall is calming down in the same way his clearly autistic son does. Both of them are overwhelmed by the family dinner, so they sit outside and play with Legos together, an act Rava, his ex wife, does not engage in. It's parallel play, they're sitting together and calming themselves down side by side, not necessarily playing together. This is very common amongst autistic people.
And Kendall, like many autistic people, wants to emulate those around him socially, so he can be liked the way he thinks his father is. Kendall often incorrectly assumes that if he mimics all those around him, copies their social skills, pretends like he fits in, people will finally see him the way he sees himself. And Kendall really is a good person. At least he tries to be, having that much wealth and power is always going to make you a bad person, especially when you don't take the steps to deconstruct these power structures. But Kendall wants to be a good person. He wants to do the right thing. He tries hard to be the involved father, the perfect son, the kind boss, the fantastic husband, the good friend, the caring brother, the greatest business man, he wants to be the most loved, the most loving, the person everyone likes and who fits in. But he can't navigate it quite right. He's understanding of how to grow Waystar Royco into a business that's successful in the internet age is actually quite spot on. His desire to create what he views as an inclusive environment, a respectful one, is genuine.
But Kendall cannot fit in no matter how hard he tries. And I don't think it's just because of his wealth, though it plays a factor. His siblings, in particular Shiv and Roman, especially Shiv, are considerably better socially. They, like many neurotypicals, can become social chameleons, changing how they interact and act to fit in with whatever crowd they're in. They're out of touch due to their wealth, certainly, but there's a difference. They socialize well in the wealthy circles they grew up in, they transfer these skills to other social circles, they socialize so well they can advance their career. Noticeably, they lie well, they can pick up on when most everyone is lying to them, they can navigate all of their respective spheres well.
Kendall cannot do these things really, when he tries he always falls flat. Even in out of touch, wealthy circles, he really cannot fit in. His inability to be the person he wants everyone to see him as is two fold. His wealth and abusive childhood is one dimension of it, he doesn't have good footing for where to start, so when he genuinely tries he falls flat on his face. But he's autistic, compounding these issues. It makes it much harder for him to actually understand what to do, how to do it, and his only guides through his life were wealthy people constantly working to undermine him, to cut him down. Shiv and Roman, not so much. They know what is the "right thing" and what is socially seem as the right things to do, and they can adapt their presentation to match that. Shiv knows it's socially acceptable to be a democrat, and so she is, though she isn't one. Kendall cannot, and though he tries to do the right things, and he tries to do them because he sees them as the right things, he cannot conceptualize a life other than his own, cannot fit in, and with no other guide but his father, cannot be the person he truly wants to be.
His attempts are genuine. He tries very hard to be an excellent father. He loves his children. He is by no means good at it. But he wants to be. And he makes greater strides than his father ever did, and in many ways for him this is a great effort. He is pained by how no one seems to like him, no matter what he does. There's this scene in the first season, where he looks at the falling stock price and tells his brother, "this is how much no one likes me." In season three, he tries to get people to like him by being self aware about how much they hate him, tries to let himself be made a mockery, because then maybe they'll want him. But he doesn't understand why they do. And it becomes a form of self harm, like maybe if he lets them hate him to his face, he'll understand why they do emotionally. Sometimes he understands objectively, but really he doesn't. And he self medicates to make it easier.
Kendall noticeably does drugs the most when he is struggling to fit in socially. Before therapy with his family, because he wants to fit in with the group of people he's with, wants to fit in back home. Also a very common autistic experience. It seemingly makes him likeable, makes him comfortable, lowers his inhibitions so that maybe he'll fit in, and maybe he'll get over his fears.
Kendall's struggles as an autistic person become Shakespearean in height due to the wealth and station of his life. It makes you wonder if one moment of his life were to have been changed. Say he doesn't get into the accident with the waiter, he'll escape the grasp of his father, and probably he'll have the means he always wanted to create the meaningful change he longs for. He stays committed to outing his father's negligence on the cruises. Something different, something new. Hell, even just a diagnosis, and I'd bet Kendall's life looks utterly different. It allows him, at the very least, a modicum of comfort and understanding of his life. Best case scenario, Kendall has the tools to navigate the world, and as such, can become the very good person he feels he ought to be.
Kendall Roy has autism. And autism is not tragic, but him having it in a world so hostile to him, without the knowledge of his autism, is.