in my experience, the inkubi are into possession, and like the dibbik, dibbuk, etc (aka the boggart in harry potter), can cause physical manifestation of their possession - they physically use your body to manifest what you most desire to become
the sukkubi and of a roman origin as afar as i know and are external, women (as far as i know) who come to priests and monks and get them off in the night) - their torment used to explain the stains on the sheets perhaps
as for calling an inkubi, i don't think i'd go there but you could try - you could use the xtian method of opening your heart and calling for an inkubi to come and live inside you, then giving it full control over your life - nah, that's just whacked
calling a sukkubi is easy (imo!) for they are associated with lillith and the moon - just get physically connected with the universe (using one of the many meditation methods on this form) then call for one to come in the night - the problem starts when you meet somebody and you need to get rid of the sukkubi 'night companion', cause they won't go without a fight and i've had them scare off a potential rival before i got the chance to make my move
gee, they remind me of a lower-order jinn! (tee hee)
e.
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