ask yourself and try to feel what in your Demon will make you most happy and comfortable, and tell Satan this, don't try to choose Demon yourself - because we don't know every Demon in Hell, - just tell Satan the personal quolities which would make you happy. for ex, tender, warmth, just 1-2 things that you need the most. Such things as passive-active role preference, male/female - if you know what you want, if you dont know, you may simply ask Satan to give you Love that will make you happy, or wait and proceed in meditation, because meditation will help you know yourself, it will show you your own soul.