Small hack for the "tell me about a time you worked with a douchebag" story: add lots of humility. Take a story where you thought you were reasonable, but someones else could have seen you as a douchebag, and tell a heartwarming story about how you can understand that now with a bit of distance and how you've grown so much as a character.

(My story is about having to work with a cowboy coder on the same codebase, but the cowboy coder happened to be the boss of our sister team and had lots of apparent productivity and was thus loved by higher ups. The humility comes in from describing my own attempts at improving the situation but failing. Basically, you catch more flies with honey than vinegar.)