I reckon it's more likely to be Rose (4) Tyler (hmm, only 5 unless I can't spell!)
But this is not a game I am interested in, so if I'm right, give it to Swizzle for being nearly there!
;-}

Cassidy Sharp?

new clue added

Cutty from Thief: The Dark Project

Gratz! Code on the way

I may not be the best clue maker, but...

Cutty is sharp (at least cutting is).
A fence (cutty's profession, can also divide property)
His cell was block 4, cell 6 as referenced in the office journal
He starts garrett off on his first mission to steal the sceptor and later provides info that moves him to the main story arc.
You knock people out in the Thief games

;)

Thanks for playing.

Congrats Somnambulist!

Well, you capitalized "Sharp", which led me to think it was a name.

But never mind. I have the originals, and I'm pretty anti-Steam anyway, so it's all good ;-)