When Deuce goes to Cater on the topic of his being unsatisfied with Riddle (after seeing Cater’s dream of Book 7) Cater denies it, saying he isn’t “totally happy” with Heartslabyul but he is not interested in unseating Riddle, and would lose even if he tried.
Idia describes Deuce as “Honest to a fault…or maybe just all fault.”
Cater insists that he and Trey “are cool, caring, dependable upperclassmen.”
When Leona asks if Deuce actually believes such “hot air” Deuce responds, “No! But then again… Cater looks out for me. I’ll believe what he says!,” and Deuce actively choosing to believe people even if it go against what he knows about them is possibly a theme:
When Idia points out that Ruggie might be unwilling to share food with him Deuce responds, “I’m sure if I put in the work, Ruggie would be willing to help me…at least, that’s what I choose to believe.”
When Azul assures him that he may sign his contracts indiscriminately Deuce responds, “Oh, really? Well, I guess you DID just give me back my spell without any fuss…” (Riddle: “Deuce! You’re letting Azul swindle you already!”)
When offered the option of going to Trey or Ace’s dream worlds in Book 7 Cater choose Ace for Deuce in order to reunite the first-year quartet.
Ortho observes, “Deuce seems to be in higher spirits already now that he’s got an upperclassman from his dorm here.”
When Cater shares his plan of trying get the darkness of Ace’s dream to wake him up on their behalf Deuce volunteers to help, saying it is too dangerous for Cater to try and do by himself (Cater refuses his help, ultimately going alone).
Twisted Wonderland Reference Note 