"Guy who knows the protagonist from way back when and just fucking hates them for some reason and is constantly trying to re-litigate some ancient beef" is an undervalued tool for expository worldbuilding.
Unsub!Reader: *blushing* So... You find me interesting?
Hotch: That's not what "person of interest" means.
Price: The bread from there tasted like cargo pants
Gaz: That’s specific
Soap: Why do you know what cargo pants taste like?
Price: you’re not getting that story out of me. I will only share that I was in that situation because of Ghost
Gaz & Soap: *turn and stare at Ghost*
Ghost without looking up from his laptop: What happens in Vegas stays in Vegas
Gaz & Soap:
Danny: I’m happy! I have great friends, a great family, and a pretty good life!
Me, opening my word doc: No you’re not.
this salmon slammin' saturday, the salmon slams back!