Just moving this out of a thread rather than dilute it …
Well, I turned down the only invite I had from an Incubus, so I can mostly only go by that interaction, the interaction with other daemonics, and what I’ve read of other’s experiences. I suspect aficionados of succubi/incubi interactions will have other ideas.
(The lad that wanted to connect with me was very sweet, appeared to have a well developed personality, and wanted a relationship not just sex, where we could meet in astral locations and just talk. I didn’t sense him take any energy on the couple of times we met, at least, not enough for me to notice, but it was early days. )
I think you’re already hitting on the point of contention - when does parasitism become fair exchange?
By the basic definition of parasite, ah, depends on the entity that’s telling the practitioner that’s it’s a succubus/incubus - quite a lot of parasites masquerade as these but are not. Stands to reason really… I do feel that there are many black magicians that genuinely think they have an entity from Lilith’s legions, and don’t, so, when they post about this, it muddies the waters.
The test is super easy though - parasites live on or inside the host, so anything that attached to the aura and lives with the practitioner, daily taking energy, is a parasite. Daemons, even lesser daemonics from the legions as incubi/succubi are, don’t attach like that - they don’t need to, as they have fully developed systems of thier own.
BTW I think it also applies perfectly well to some humans. It’s a term I actually use for an ex bf of mine that was very incubus-like - I can be bought with sex, apparently, much to my chagrin 
- but he was otherwise a useless freeloading leech. He wasn’t able to support himself, he inserted himself to my life and sucked it dry… parasite.
As I understand it, while daemonics enjoy the sexual energy (a lot do), they won’t wither without it . Succubi/incubi specialise in it, it’s more like a lifestyle choice, but they don’t feed on the practitioners energy otherwise - it’s the sex part that’s tasty, they can get regular energy elsewhere without risking the practioner’s ability to, ah, put out 
That makes succubi/incubi vampiric feeders, I’d agree with that.
But not “vampires”, as vampires can’t feed any other way - that’s what makes them vampires as opposed to energy workers that also enjoy leeching off other entities. Vampires (human-skinned or otherwise) are usually parasites that attach a tendril and stay attached.
That they can have feelings and “love” you… Others say … that some do care and form a symbiotic relationship with their human
I think they can love - romantically, sexually, spiritually, intellectually, fraternally, paternally … all of these and more layers inaccessible to humans. In most cases they can do the human versions better than humans. I think humans with thier limited bodies are not actually capable of feeling or sustaining access to the full range of emotions that higher beings can, and their fickleness and self-focused hedonism around love leaves me frankly contemptuous.
I never believe a human that says they “love” me. Not a single one - it’s always a self-serving self-lie. What they always mean is, ‘you make me feel good’, and their “love” only lasts as long as that continues, and it’s easy.
I do believe the entities, again, if they are daemonics not parasites/impostors.
And in this case, when the entity is an actual daemonic and not a parasite, you have a similar relationship to the ones people have with Azazel, Asmoday, Sitri and other daemonics that have a fetish for entities wearing human-suits.
As such, you are, imo, in a better position in a love relationship with a succubus/incubus than a regular human, except that, you may miss other practical aspects of human relations.
Again I’d have to work on building experience and I might change my mind, (which I have zero intention of doing) and it would have to directly contradict prior experience, but that’s where I stand right now.
