When we write we put our heart and souls into our characters. They become a part of who we are. But are those character verbatim of who we are? Of course not. We “tilt” the character just so, so that he or she has something similar to who we are. There might only be a smidge of something about us but it’s there.
Tilting the characters makes them in their own right individual and unique. But if we don’t put ourselves into our work it won’t sound right.
No, I won’t be a thing like the antagonist. But I get easily frustrated and so does my antagonist. So I tilt a part of myself and put that into my character. It will make him or her all the richer for it.