It's a constant theme in the anime revolving around Ace's question of if he deserved to be born or not and this struggle he deals with right up until his death. So I wanted to elaborate on that from how my interpretation of Ace faces this self-loathing and hatred.First of all, he's never actually suicidal. Though it can sound like it from the outside, he never once considered taking his own life for two reasons. The first, and main reason, is the sacrifice that his mother gave by protecting him with her life, literally keeping him from being born for months to ensure that he wasn't killed upon his birth by the Marines. The second is the need to prove to himself and the world that he does in fact deserve to live, regardless of who his father is.How this affects his personality is huge.Because he'd so aware of this darkness and how crippling the self-loathing can be, he goes out of his way to look for the signs of it and other abuse/trauma in others. He is the definition of the kind of person who the brighter the smile the greater their pain. Trying to be a source of warmth and light for those around him that need it while all the while remaining silent about his own internal struggle.This is why he's always laughing and smiling and from the outside appears as this warm happy go happy-go-lucky guy to those he doesn't see as a threat. It's why he's polite and caring and will go out of his way to help others. Why he is essentially just this big brother to everyone that needs one, or an attentive lover even if it just for the night. He wants to make sure that everyone he meets knows that they are special. Because at the end of the day, he doesn't want anyone else thinking that they aren't good enough like he does.The only people that know of the true depth of his pain are Sabo, Garp, and White Beard.