Week 5: If you have ever had a character try to push their way into a fic, whether your "muse" or not, what did you do about it?

I've rarely had this happen with a character who wasn't slated to be in the fic in the first place. The few characters that have suddenly burst into full bloom have almost always been minor canon or original characters who are only there to provide structure, atmosphere, bits of exposition, or momentum primarily by giving the MC someone to talk and react to (i.e., the written equivalent of props and set dressing); examples are the two captains (and especially Captain Nan) in World's Worst; Noroshi in Face Voice Hands; Magus Ramalket in Deceiver.

I generally let Unexpectedly Lively Characters have free rein to see how they'll behave and where they'll go, as I think that a character that's  sparked for me might be more interesting for readers as well. The only time I can think of that I have sidelined such characters was the first draft of Chapter 7 of World's Worst. Two OCs there—Tessa and Ironhewn—came from nowhere and were certainly a lot of fun to write, but ultimately they were cut because, not  only did they slow the narrative down, I had no idea where to take them after their first appearence.