The behavioral round scares me more than the coding one. How do you not blank on 'tell me about a time…'?

I can grind algorithms for hours, but the second someone asks 'tell me about a time you had a conflict on your team' my mind goes completely empty. I either ramble for four minutes with no point or just freeze.

Do you all actually script these ahead of time? It feels fake to memorize stories, but winging it clearly isn't working for me. How do you prep for something this open-ended without sounding rehearsed?