James Moriarty was his greatest ally, and everyone knew it.
Seb never laughed at little Jimmy when they were kids. Jim was too brilliant for that.
He got whatever Jimmy needed. Toxins, weapons, you name it, Seb could find it.
Jimmy helped him, got him out of a rut, gave him someone to look after. Jim was cleverer than anyone on the planet and knew it. Jim made sure he didn't get lost in the tide; become what he was meant to.
When Seb helped him out of a prison sentence it was the high point for both of them.