I'm going to go ahead and break fan-boy boundries here (Sorry to those of you that are), but I'd live either in the Zelda multiverse or the Halo universe. Either one would be awesome.
Trained as a spartan in the halo universe, used to combat the covenant. (I'm old school - Humans and Covvies were always meant to blow eachother's brains out.);
Or end up as some strange assistant or helper to Link.
Most likely not original choices, but they'd be what I'd choose.
Now that I think back on it, the Starcraft Universe would also be rather strange. Cerebrate, anyone? I mean really - Who hasn't wanted to have millions of servants under their control, willing to do whatever they're commanded?