Jenny
It's metaphorical, I think. If you give up your soul, you go bad. You turn into the kind of person this Sam is. ...the kind of person this Tenth Doctor is, the one that looks like your dad but isn't. You only care about yourself. It's like becoming a rabid dog and you don't know any better, but you hurt everyone around you.
You can't just hand it over like it's a literal thing, but you can spiritually give it up to the dark side, it sounds like. I wouldn't recommend it, though...I like you just the way you are, sweetie :)