Remix thoughts

I've spent an enjoyable weekend reading a lot of my assigned remixee's fics, trying to work out which one to remix. I think I've found the one to do (it almost sang to me if you know what I mean), totally in tune with my sense of humour, drama and continuity. Only trouble is - I can't quite see a way in. How I would remix it is totally baffling me at the moment.

What is a remix exactly? Just how far can you go with one? Change the ending? Re-arrange the events in question? Add stuff in before what happens or afterwards? How far can you go before you totally lose the original fic? And just how dramatical/meglomanical/existencial am I going to go in this mini-rant/questioning of teh universe? *grin*

Last year I had a similar problem, as the fic I was remixing jumped around in time and it wasn't until I totally threw away the close following of those jumps and just told my remix sequentially that it worked. I suspect there's something like that here I need to do.