My first roleplay was actually pretty hilarious now that I looked back on it.
It happened on Facebook around two or three years ago. I decided to create a roleplay revolving around the Legend of Zelda. Basically, the story was that a few volunteers and myself were supposed to go into this underground dungeon maze thing to find Link, who is being held captive inside, I can't remember by who. The only rules were that each volunteer had to choose one weapon and that weapon was the only weapon that we would use throughout the story.
Anyway, everything was going great for a while. Everyone was on the same page, for the most part, that is, until one of the people who joined the rp, goes completely awry in every way you could imagine.

Dying or getting seriously injured every five minutes having to be brought back to life either by a bottled fairy or some other means the person makes up, kept adding things to the story that didn't really make sense, transforming into a zombie bone dragon for some reason, which was really cool and wouldn't really bother me if this person didn't constantly try to be the center of attention the entire time.
It became less about finding the Hero and more about this person's struggle or dilemma (whatever it was). And when I finally decided to do something fun in one particular scene and everyone was on board with it, the dude pretty much made it apparent that he/she was not happy. It seemed like this person wanted everything to be his/her way rather than just let the story play out.
Other than that, the rest of the rp was super fun! Everyone enjoyed themselves and so did I.
