I have a warlock PC, who has left the nature of their pact fuzzy, and I'm going to fill in the gaps to help drive the story along as necessary.
How powerful does it make sense for the fiend to be? Could it be any devil, or does it need be one near the top of the tree (so it can potentially power a 20th level Warlock)? I can see the potential humour in the patron being an imp with delusions of grandeur, but this could cause some headaches with the Warlock being vastly more powerful than their patron.
I'm also considering having a devil antagonist (Rakshasa) to the party buying out the Warlock's contract, so I want to gauge if this would necessarily be a step up/down.
I understand the rules are vague on this, so I'm mainly looking for what would narratively make sense.