plausiblefabulist spoke sooth:
That may be a social-contract problem which needs an off-table solution; but if so, killing the character certainly doesn't solve the problem.
Out of character, the group needs to discuss their characters a little bit more. Killing Badass' characters nine times in a row would merely drag out the un-awesome experience for the other players. But if Badass can explain the (probably obvious) nature of his character's personality in a way that the other players can see as a thematic issue, then we're good.
And maybe you can solve the problem in the fiction, if you treat the fiction as an arena for exploring it.
Absolutely This! But since this is a social contract issue, you do want to set up that conversation
out of character. "Let's talk about your character," you say, turning to Badass. "I've noticed that he's really balls-to-the-wall and doesn't seem to respond rationally when faced with danger or opposition. What's the story there?" Be careful with your tone here: You are not
confronting him; you are
expressing deep interest in the psychology of his character. What you're digging for is a
Theme that will allow the other players to view his character's personality as a deliberate creative decision. Maybe he hasn't thought consciously about it yet. That's okay, just keep asking questions until you get to it.
"Well," Badass might say, "Now that you guys have been with him for a while you've probably noticed that my character has some deep-seated emotional issues, and his propensity for violence seems to be his way of acting out, a way of redirecting some inner conflict. The problem is, he isn't really conscious of any of this. He's walking around filled with rage because of these suppressed memories. Shit, they must be something horrible." He doesn't need to tell any "secrets" and this isn't a Read roll, but suddenly everyone has a new angle on this guy. Suddenly we have options. Dramatic, meaningful, options.