If you must know, my 'base' version of Shadow is the one from Shadow the Hedgehog. Probably where all that 'edge' comes from. That's not to say he's written exactly the same (because that was some god-awful writing). But I didn't play that game through 326 times because I enjoyed the Westopolis level.
It's just when I write him, I'm like, "During ShadsTH Shadow was a total asshole who only asked for help when he thought he could beat it out of somebody, and yet he had the corresponding sense of humour that an asshole would have. Also, alien hybrid." So he has moved on somewhat, but one thing's for sure - he's not quit being an asshole just yet.
What the hell. You are what you eat, eh? ;)