I think 'I met this man during an interdimensional death ritual and he was actively working with the perceived enemy' is hard to upstage as far as untrustworthy entries into your entourage go.

[ McGillis does have some self-awareness about this. Hubert is extremely valid. Of course, McGillis won't trust him either because he has very little interest in being eliminated due to being perceived a threat to Edelgard's safety... ]

Have you told him any of that truth?