Remus / Sirius
It wasn't like Sirius was dissecting their own behaviors daily or anything, but he did turn an introspective eye inward every once in a while -- just to make sure everything seemed fine, and that he wasn't being too annoying, or whatever else it was that he worried about sometimes.
And what he mostly got out of it was that he knew he loved being around Remus (because he loved Remus, full stop) and that Remus seemed to love the same thing. Their behaviors were normal for who they were and they just... liked it about each other. So it worked. Really well.
Sirius -- another biscuit half in his mouth, looked over at Remus with an assessing sort of look, and then stood up himself -- reaching for his own wand. Did he think whatever that noise was was a big deal? Not really. But Sirius rarely took much -- well. Seriously. On the other hand, he trusted that Remus had better senses for these sorts of things than he did. So if Remus suggested leaving, he wasn't opposed to that concept. "That's the door, though," he whispered back -- and sure, they could apparate, but in order to do it well they needed a plan first.