My play group is currently running a prototype game we made based on Dragon Ball Z using d20 rules; I'm GMing. One player in particular always makes characters that are mentally limited, crazy or with really weird powers, and it usually makes him not take things seriously.
He is currently playing a character that essentially is substituting his own reality on the story. For example once when he was prisoner he interpreted his cell as a hotel and all the guards as employees of that hotel. He spent the entire adventure asking for someone to go fix his room and for management service.
I wouldn't normally have an issue but I plan to run a whole mission about choices and paranoia and I have no idea how to make it so his character would actively partake in it and bend to my story like everyone else. How can I handle this situation and have him play his character straight and not as a lunatic?