My suggestion is to avoid any cringey back story. Seems like all characters have some edgy drama they center on. Instead, have a really boring backstory like you’re a retiree who is just looking to pass the time. Something you can kinda chuckle at to break the tension with having to roleplay.
Or, if you have to have an elaborate backstory here is one I’ve used: your character’s mind broke after whatever happened (like old age) and they believe they have made a pact granting them warlock powers. They don’t have those powers and are just going batty, so just work it out with the dm where you “cast” hexblade but just do a normal attack. So you’re just a fighter really but you’ll be pretending you aren’t with the other players.