because I think Stephen wouldn't know how to say no when things started to get out of hand.

Oh, Stephen definitely wouldn't. He has limits, but he's so caught up in, "I have to be a good boy!" that he'd never say anything about them, for fear of disapproval. Brian would definitely be able to read him pretty well and figure out what he wanted and needed.

Haha, well, they were very convincing, whatever they were. ;)