Fan Casting I Let Gwen Stacy Die in Sort by Tropes

Often, a hero needs more of a reason to keep on fighting than just to save the day. He needs to know that it's fairly Serious Business. That's why, on occasion, someone close to him will die for generally no other reason than for the hero to angst over his inability to save them, driving him to protect everyone else he can. If something is almost certainly going to result in a "You Did Everything You Could", "I Should Have Been Better" exchange, it is defintely this trope.