Ace is an original character, though he is possibly based on the Knave of Hearts. He is the knight of Heart Castle and often forgets how to get to places. Though, seemingly harmless at first, he becomes more devious over time and demonstrates a tendency towards violence. He is one of the first characters to admit that he has no romantic interest in Alice, though that changes shortly after he says it. Ace uses Alice as a shield when Peter threatens to shoot him and he helps Julius Monrey collect clocks from people who have died while killing those who get in his way.
Source from Wikipeida