the pull toward underground ventilated private
when he’s tired and on edge and would far rather go off by himself and do secret stuff in underground ventilated private.
Context
The Big Buddy sessions are only unpleasant on the days the pull is strongest — when what he wants instead is to be alone underground with the exhaust fan. Named flatly and in passing, the preference for solitary using over the company he's responsible for is the tell the program would catch instantly.