Abe Kusich is the grumpiest dwarf we've met since Gimli. Although he's a cantankerous fellow, he somehow gives Tod the inspiration to keep painting.
There's one important thing that separates Abe from the rest of the characters, however—he knows exactly who he is. Sure, "the person he is" just so happens to be "a growling puppy" known to make "mad rushes" at his friends when they anger him, but we're okay with that (2.77). Would it be better for him to be as unsure about himself as Tod? Or as insecure as Earle? Abe will chase women and throw fisticuffs with the best of them, but he doesn't come out the other side in a depressive funk—he just goes home and sleeps like a baby.
Abe's life probably isn't changed much by the events of the novel. While the rest of the characters' lives have been greatly affected by the book's tumultuous events, Abe brushes them off his shoulder. This is like an average Saturday night for him. And perhaps it's this inherent griminess that makes Abe such a perfect painting subject for Tod.