Bestowed Demon

You call upon the gods of the underworld to bestow you a demon servant. It is up to the DM's discretion how powerful the servant is and which god summoned it. The demon is loyal to you and only you, it will not take any orders from anyone but you even if you say otherwise. If the demon dies, it turns to ash and cannot be brought back to life. If you die the demon continues to live and will now only ever take orders from the god which summoned it, even if you are brought back to life. 

For instance, Orcus may use this opportunity to get himself into the Material Plane by summoning a powerful demon, such as Glabrezu which might have a chance of one day being free of the summoner.