Earlier quoted context omitted.
For real. Off the top of my head there's, MeerrrOOOOOwww MerrrOOOOwww, the loudest one, huge inflection in the middle. Generally while strolling through the house, back and forth. I think that's the "I'm bored" one. But he'll also do it if I stay up. If someone is out of bed past curfew he'll do it. I have to close the bedroom door or he'll wake the wife. If you say summon him he'll probably ignore you but if he's in…
Do you also get a BRRRP or MRRRP when he's snoozing and you put a hand on him? Our cat does that. And a similar noise to say "hello" when coming into a room or approaching you.
He's sweetest when he wakes up, so it turns into more of a coo than whimper since he's purring a bit.
Seems to be his hello/greeting call.