The 10th Doctor has often seen on the verge of going too far (imo) take killing the Racnoss, and his face when Mr Cooper made his comment about what kind of a monster he'd be if he decided who lives or dies...well I'd like to see 10 go too far, and in effect have to regenerate to save his soul.
He'll probably go out battling a gazillion Daleks though...
He'll probably go out battling a gazillion Daleks though...