Jon goes back in time to stop the Apocalypse from happening and then somewhere along the way realizes he can’t stop it, but he can control the way it happens. He will always be the cause for the end of all things, so might as well embrace it.
Elias finally found his Archivist and he’s not likely to share what belongs to him. Martin is jealous that Jon is spending so much time with Elias, but he also knows it is hardly his place to do or say anything about it. Jon’s not his and he can make his own decisions. Even if they’re horrible decisions.