To ask if I've been blocked on Facebook?

[Hazysummerevenings]

Person doesn't appear in my searches, or on our mutual friends friends lists. Yet when I go into messenger and type in their name, our old messages come up and they have a profile picture etc there?

You will only be able to tell by searching via someone else's account, I think.

If it says facebook user with a shadow profile picture then they have blocked you, but if their pp is still on messenger they have left fb but stayed on messenger

Ah okay. Looks like they've left FB but stayed on Messenger then, thanks!