Came to say the same. He was under so much mental abuse, he had to do stuff to survive. He's an accomplished man too, but he was forced to go through all those degrading crap. That's too heavy of a blow to his self-esteem. If acting like a child could make his abusers hurt him less, even if it's stab to his ego, he did. And it became an unfortunate habit. ╥﹏╥
It's hard to unlearn what became a routine to him in this new world.

Some of yall that hate Chika for his behaviors have never heard of age regression as a legitimate trauma response. The novel is sooo much more gruesome with his sexual abuse and it makes sense why he would regress mentally to being younger