The Traveler of the Far Realm
Not all warlock patrons from the Far Realm who answer the call of mortal petitioners possess alien and unknowable origins. The Traveler was once a crew member onboard a spelljammer that ventured, either by accident or design, into the space beyond reality known as the Far Realm.
Many legends about the Traveler claim that he or she was the spelljammer's captain or its navigator. However, all tales about the Traveler agree that this was to be a tragic journey; the Traveler's companions were all destroyed by the unthinkable horrors of the Far Realm, and the Traveler was driven insane and warped into an immortal, eldritch thing by the corrupting influence of that malign plane.
Although they were born neither an Elder Evil nor an forgotten god, they have become a Great Old One who sometimes agrees to make a pact with a would-be warlock, granting them arcane power and steering them toward obscure ends.
Dread Possibility: The Desire for an Earthly Vessel
What is it that the Traveler of the Far Realm desires? One horrifying possibility is that the Traveler empowers its warlocks because it is searching for a mortal vessel into which it can transfer its life force to escape imprisonment within the Far Realm. It may be the case that the Traveler is priming its mortal petitioners by granting its pact-bound warlocks increasingly powerful arcana--essentially acclimating their bodies to the level of power that possession by the warped remains of the Traveler's soul would require.
