Picture this:
Upon reaching level 75 of the Reaper's Bones and getting the Champion of the Flame title, you unlock the ability to go to the center circular platform of the Reaper Hideout and play the "Who Shall Not Be Returning" shanty, which will cause the platform to lower into the full hideout.
Once you're down in the hideout, you're met with more servants of the flame who offer you the cursed chalice that turned Captain Flameheart into a Skeleton Lord. They offer you to drink from the chalice (could simply work like a tankard) upon drinking from the chalice, the Skeleton Lord's Curse is added to your vanity chest (and is immediately applied to your character upon drinking). You are also given a full Reaper's Bones Outfit to use (like being given the Legend Outfit when you hit Legend).
I figure all of this would be cool since the Reapers are anti-Athena's Fortune. It would be like their own petty way at getting back at the Pirate Lord by holding their own induction of high level Reapers similar to how you are essentially inducted to Athena's Fortune when you hit Legend.