Ace says that Deuce needs to “stop assuming everything’s a fight,” and violence is Deuce’s first resort in many situations: he first intends for his duel with Riddle to be physical, not magical, and he would have possibly punched Riddle in Book 1 if Ace had not gotten to Riddle first.
(In the novel the prefect holds Deuce back from attacking Riddle to keep him from getting expelled again.)
Deuce is happy to take Jack up on his offer of a fight in Book 2, attacks CHARON in Book 6 to try and save Grim, and fights are a regular part of school at the NRC of Deuce’s dream world.
Deuce also tries to fight ghosts (multiple times), says he wishes they could solve the Magicam Monster problem of Halloween with their fists, and when Malleus visits him in class his first assumption is that Malleus is calling him out to fight.
Deuce challenges Malleus directly (“I’m ready to brawl ’til one of us can’t stand up anymore! BRING IT! C’MON!”), but Malleus fails to understand what he is going for.
Deuce also calls for Rollo to fight him, decides to “let (his) fists do the talking” during the Wish Upon a Star event, tries to fight Idia and bullies.
After the footrace of the White Rabbit Fes event Deuce’s mother asks if he is all right and he responds, “I’m pretty used to scraps like that.”
When Deuce’s tsum proves to be violent Ace observes, “The way it flips out at the slightest provocation is totally (Deuce).” Deuce tells his tsum, “You really gotta do something about the way you let things set you off. Otherwise you just make trouble for everyone!”
Deuce tells Sebek that he is always levelheaded.
Twisted Wonderland Reference Note 