Max Bemis 
Oh, Killstrike #1 [EPUB ebook] 

Jared, a new father, fears parenthood. An old comics fan, he turns to them for comfort. But when he unwittingly lets loose his favorite character, Killstrike-a single-minded, vengeance-loving anti-hero-onto the world, Jared must find a way to send him back before he harms all the people he loves the most. But before that happens, Killstrike leads Jared on a quest of self-discovery to make him realize the kid who loved this character is not the man he has become.