What if Azazel had given *both* boys his blood instead of just one? (Maybe reverse verse isn’t a good term for this then? Just an au??? I dunno.) I’ve seen reverse verse where Sam or Dean is an angel instead of them being brothers but I’m a little too attached to their dynamic to make them unrelated.

I’d consider that more of an AU probably. Or if it was wincestiel and Cas was a hunter and Sam and Dean were angels. I kinda feel like reverse verse implies that the main pairing (or triad or quartet or whatever) has their backstories switched. So, like, Dean would be the one to have the demon blood, not Sam. Though, that would be a really fun au to explore.
Also, I think Swesson is the one exception I make for relation. I want Sam and Dean to be, at the very least, half-siblings.