>>118469192The expanded stories in the ACME books tells the tale: He's a little dork that literally nobody likes. Even the nice teachers just shake their head at his weenie behavior. His dad is a failed writer turned teacher after getting his mom pregnant (trying to prove something to himself after a hot woman toyed with his heart.) He cheats on her and generally hates his life, taking his anger out on the two of them. She's normally very meek and wanting to please her husband, but takes her own anger out on Rusty as well (eventually devolving into the shrill old hag depicted in the adult Rusty comics.) He's obsessed with his Supergirl doll and imagines her coming to life, because of her beauty and the concept that she would treat him like a hero. Enter Chalky, who Rusty eloquently sums up with, "He's an even bigger dork than I am!"
Thus, Rusty, the boy everyone hates, finally has the one person HE can treat like a punching bag. Fast forward to their adult lives, Rusty clearly never grew up, living with his mom for decades. Chalky followed suit, until finding a woman he quickly married and had a kid with, leaving Rusty in the lurch after his mom dies.
In short, nobody liked him, and the one boy who wanted to be his friend, he made a lifelong subordinate. His parents are to blame.