It could be that around his childhood interests he just never mentally matured, so being around them or talking about them is like turning a switch to 'kid mode'
Chris is always in "kid mode". He is mentally about eight to ten years old, and his parents never motivated him to grow up. They continued to buy him Transformers, LEGO, Power Rangers, etc. well into adulthood. And while it isn't uncommon for people on the Autism Spectrum to share similar interests or have a similar childish mentality, it goes beyond ASD with Chris. He just never grew up because he was never given incentive to.
We can speculate all day on what kind of person Chris could have become if different aspects of his upbringing were different, but the simple fact is that Bob and Barb raised Chris more like he was their grandchild instead of their son. They were elderly people who were not equipped to raise a special needs child properly and they spoiled him rotten with toys, video games, junk food, and no responsibilities.
So now you have a man (who thinks he's a girl) with mostly childish interests, a childish world view, a childish reaction to his problems, and who has been having childish delusions for the better part of a year (magical thinking, cartoon parallel dimensions, etc.). Outside, Chris is a thirty-six-going-on-fifty-eight-year-old Benjamin Franklin look-alike in drag. Inside, he is nine years old and wants to play with his toys, watch cartoons, and let all the adults take care of the adult stuff. If he didn't have to take care of adult stuff like bills and car repairs because Barb is old and in poor health, then he wouldn't. He does the absolute minimum "adulting" he has to, then goes back to being a kid again. The only thing adult about him is his desire for sex, and that has been curbed for the time being by his delusions of marriage to his cartoon characters.
