Okay but hear me out.
At some point during seasons 1-4 Elias says something ominous to Jon and then adds “an old friend of mine used to say that the only way to get rid of a temptation is to yield to it”. Jon blinks once, twice and then answers: “Elias, that’s just a quote by Oscar Wilde”.
Silence. No one ever mentions this again.
Fast-forward to the middle of the apocalypse when Martin sees Jon stumble and suddenly say, completely unprompted: “He was friends with Oscar Wilde??????”