The first and second, yes. The third is giving me a bunch of ?????

In all the fics I've ever read, I have never, ever came across the third trope @_@

Exactly in which fandom does this exist?

Although if the third trope is daemons AU then I can sort of understand...

Ask, and google shall answer: Sentinel AU - Fanlore

I may have come across one sentinel AU, a long time ago... but this is definitely not as common as D/S, which isn't that common either? @_@

On ABO, there was this Daichi/Suga fic on AO3 that left an everlasting impression www

hmm... There's soulmate AUs left right and centre though. I wonder if they're a form of Sentinel/Guide AU