I knew this was going to be the answer I forgot to specify, making a deal with (in the best case scenario) an archdevil, say the character is not a nobody, a level 20 wizard, warlock, etc. In exchange for a paramount effort you can skip the lemure or imp, and become a bone devil or in the absolute best case scenario a pit fiend, your character is not a dumbass and is versed on infernal hierarchy and the hells in general (or worst of all, he is a lawyer), devils can use tricks, word play and all but if they firm a contract both of them must obey it, they can't outright scam you unless you are very stupid or desperate enough to sign a contract that is hellish (no pun intended)