Headcanon: Marceline and Bubblegum enjoy talking to the Finn Sword. Sure Finn’s dead by then, but he’s still their shared moral compass. And they need someone to vent to.

[And even if Bonnie knows he isn’t there (Marceline has doubts), sometimes- when Marcy’s feeling just a bit too untethered and Bonnie is two steps away from going over the deep end…they almost hear him talk back].