[member="Boulder"]
Well, first I would say make sure that the person is ok with it. I don't do all too much PvP--cause reasons. Anyway, what you could do might be what I do most of the time. Write in a semi-sardonic tone. Like I lost count of the time I entered a thread with this character and he was drunk, so it would go something like, 'James was drunk.' Eventually I decided to start having fun with it like, 'James was drunk. But no one was surprised since it was James so let's move on to more original things." Or the time I wrote, 'James Justice landed his ship. However, since the writer was tired of trying to revive the same old sequence of events and make something totally unoriginal like landing a spaceship sound cool and no one cares about how the landing props extended and the engines cooled off, we will move on."
So on and so forth.
I suppose the main thing would be to know what the player your writing with is ok with--and go from there. Like a dance, if you will.
I would suppose if you are going to be mischievous, do your best to make it apparent its purely comical and not personal. Also, make sure that You or the situation are the butt of the joke. Not the person. Like the time I had James fighting and try to use the force for the first time--only to literally fall flat on his face while getting shot at. Weapon malfunctions that you turn into satirical imagery of society, thought processes that you nuance that are totally ridiculous, or even just personal blunders that you make into comical comebacks (Jar Jar anyone?). Or just making fun of the situation you find yourself in--these are all totally good things to do.
The key is to just not make it personal in my opinion, if you follow me.