The Devil's Advocate
So what defines the most important hire for your team or your business? I'd argue it's someone who can be a pain in the arse.
Constructively, as in being the Devils' Advocate. Although not from the slightly dodgy Keanu and Pacino film of the same name. That doesn't end well.
But from the perspective of someone who will ask the tricky questions, tell you the truth without pandering to your ego, and in a way that doesn't land a problem or a negative before waltzing away.
It's about having someone with the experience to be able to point out, logically and/or emotionally, why your idea might suck, but linked to ways it which less sucking might be creatively possible.
It's not about being a contrarian for the sake of it (annoying). Or always having a different 'better perspective' (smug and annoying). Or claiming superior knowledge (really f'ing annoying).
Positive chemistry and alignment still comes first for any good partnership. But the added value bit comes from seeing the same goal but having alternative ways to get there. A human Waze that recalculates around barriers.
So in any interview with potential partners, find the things you disagree over that can excite as well as the things you align on. Don't just hire yourself.