I’ve never attempted to evoke or summon a spirit being myself; this is something I only only starting to learn anything about. But I understand the basic idea of calling upon a being, demon, angel, elemental, ect, to either carry out a task for your benefit, or to provide you with information. The question I have though is basically why would they want to help us? Why should a powerful spiritual entity, want to tell us anything at all, or to do us a favor because we commanded it too? What’s in it for the spirit? It only stands to reason that it must somehow benefit both the entity and the one that called upon it in the first place. As I said, I am new to this idea and have never actually done this myself, but still I cannot possibly imagine a powerful demon for example, thinking itself a servant to a mere mortal for little reason.
I’m going to offer a general answer based on only a couple months’ experience in evocation, and which is going to be somewhat wrong by the mere fact that spirits have individual personalities and motivations. But, FWIW: because spirits desire to act on the material plane, and the sorcerer acts as a doorway that is otherwise not available to them.
It seems to me that some demons just love and desire certain outcomes and experiences so much they’re willing to get involved with anyone working in that general direction. A bit like, if you have a favourite sport or hobby or some other interest, and someone asks you for your advice or a bit of help, you won’t resent the time nor see it as being the “servant” to their aims, because you enjoy it too.
You would seriously not have to make blood sacrifices and offer your immortal soul to get me talking about Dr Who for example :o) and in my experience so far, as well as what I’ve learned, they’re much the same.
This is my personal theory so far explained in full: “Psychology of demons.”
Other theories that lean more religious are that demons each correlate to specific areas of lust for worldly things in order to tempt humanity to its doom by turning us away from God and towards being bound up in those things, and that they must either be completely rejected for that reason (standard religious idea) or mastered by the magician acting as God to overcome those material things, by acquiring enough power over them that the fear-based attachment falls away, and the magician becomes perfected in mastering the material world whilst in alignment with God, but I don’t personally believe that’s a very valid way of looking at things.
Nonetheless those are out there as popular ideas, so just mentioning them for whatever they’re worth.
Indeed I’d say that is more than just a question seeking the stock-answer… rather an inquiry… why would?
How does that understanding fit into how “this stuff” works (more so, or at least separate from the techniques)… it is related to the question why would a person-human want to help? (similar lvl- whatever that is, as develop power… let alone a much more “Powerful” ReSource-full)
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I just wrote a number of references to this in my recent posts- some have different views, but I’d think- the “relationship” develops over time… (any you can say- Hey would you do XYZ? by the way nice to meet you… is gong to be a different issue than one that you’ve linked to.)
-they know you, you know them… Oft a Powerful- Entity or person, will reach out and help, an inspired “seed” that seems to show potential and has demonstrated a CanDo (thus, I think a part of Doing a regular practice… witnessed it is seen as showing your basic “followthrough capacity”… as a basis)… Of course any you could meet on a good day, right time-place… they see what is needful- little tweak…
but oft one associates with a “similar lvl” (demonstrated) but also where you go… (what crowd-enviro- “frequency” did you meet XYZ… again Spirit, or person- oft think use Sigil and Name and meet the same… not all equal- not sure will answer (another instead?) … or even if the Daemonic Power, or other Entity… send an Underling… just listen to what you say and they send Encouraging Presence… but act in tandem?
Others might give the idea of Human’s that assert their divine right… from the RHP background (even if using the LHP)… is one way, but I find the above context can help- then think of reaching out through a sigil… like visiting a “place”…
who is there? type of place/crowd?
what type of vibs do you send out ‘there’? attracts to you- and attracts back to your WorkingSpace? (insulated from, or blending into your life?) …
how might you get introduced-onward? (how might you demonstrate value-prove your self- not in a big obvious way, but in showing candoitness…? or whatever that means…)
There are Big Actions you can be asked to do- interupts everything, or a little thing- easy to do, harder for… and likewise for “The Other” (compare that between 2 people- or in context of Spirits… how ‘easy’ is it for a spirit to move a rock? but for a person- pick it up and carry it 100ft? .
likewise, there are things that contrarily are quite an effort for a Mage to do (and perhaps impossible for most- like Entity moving a solid object) but for an Entity, Energy, Being… whatever- perhaps different for each kind… but easy for them- that might affect our lives alot… it is how
-thus End-result we seek… Spirit may see ah -to get that, just this … but if we explain to them our ways… our world… confusing (and wrong state of mind for us anyway to Contact 
and biggest pt, as I’ve been salting in my post-comments (this is my view) not all Spirits have the same impact… like having a Team of people that is filled with those “watching the clock” all waiting for directions, Vs a “well-oiled machine” a team that is driven… Vs World-Class “Achievers” (the last can see and instantly recog- could do XYZ… and like this… first step- start now, let’s make a call, send an email… boom its begun to roll, vs it being “on the schedule” for later this yr… to think about)…
Not all Spirits are the same- lvl of 'doing' (and not "which name").. just like making a phone call: the question "May I ask who is calling?" (that is demonstrated through your presence..
and your rep- "introduced by".. to the spirit.. thus not just grab the biggest name and draw the circle and call them up... who might come, and regardless who arrives- what is the relation that is begun?
^^^
–some Spirit energies you can tell, “I would like XYZ…” and they might (as I have) had the sense of their Presence and Energy is overwhelming and they respond interested as if willing to help… .but nothing… why? Many hear “I would like XYZ to happen.” like saying- “I like vanilla icecream.” -“ah, thx for sharing… I like these things…”… Many Spirits are distant from “human-mindset” and not like having a conversation with a person, or even with a Mammal… consider a really-Really intelligent and present Insect… or Reptile. or… (just as examples)… and even that would be more relatable… as some Energetically connect and can build an assocation- you’ll assist them/they’ll assist you… but how to comm, as they are even more 'different" than the ex I just gave…
some context-challenging. might help? (if can receive from the Door that make avail- could have much more downloaded). luck in your seeking
longer response than I intended- similiar issue I see questioned, so thought I’d use the oppor to refine my presentation on this… before it drifts away again in the forum 
(and the Energies I work with prompt a bit of clarity and pts covered). -cheers
Maybe that’s what they’re supposed to do? Maybe our “job” is to learn, and their “job” is to teach, guide, help? I know it sounds overly simplified, but sometimes Occam’s Razor works.
As I see it, we all evolve through knowledge and we get it from eachother. A spirit or entity can evolve by interacting with us humans, and learn as much from us like we do through them. They simple learn through our life experiences, by standing passively and whatch.
The true power is, as I see it, knowledge. And to think interactions with spirits or entities just benefits us, and not them too, would just be too simple to explain. Our own spirit and soul could itself bear alot of power and knowledge within, which the spirit or entity could know and get beneficial from that. Who knows what our subconcious have in storage?
Right. So think about it like this: humans are obsessed with seeing things in snapshots and as single static states that change over time, like a cartoon flip book (I’m not revealing my age here, am I?) that tells a story as it flips from static state to static state.
Spirits, on the other hand, are concerned with actual movement. For them, the actualizing of the story being told is by far the most important, the medium for that be damned. Its like the difference between being aware that you’re breathing in air, and feeling the wind on your face. The human obsesses over the content of the air, while the spirit rides (is?) the current on the wind.
This concern for action, movement, change, growth, for actualizing what their portfolio is, is what spirits get out of their end of the deal. If I were to evoke a Venutian spirit to strike my enemies down, they’d probably end up down… in bed with some random person, well out of my way, and on their way to an orgasm. Venus doesn’t concern herself with acts of violence, and is far more concerned with love, sexuality, fertility and prosperity. As such, Venutian beings would want to actualize this on the physical realm, in the form of people falling in love, having sex, perhaps even enjoying a good meal together, that sort of thing.
So, even though I set the parameters in the evocation (get [asshole] out of my way), the spirit actualizes their domain (love, in this case) within the parameters I set (remove troublesome human).
I don’t know if a powerful demon, or any powerful entity, sees themselves as our servants. I know some people think of them in that context, but I’ve never entirely subscribed to that school of thought. They’re ancient beings with vast knowledge that far surpasses anything I’ll ever attain. We’re damn near embryonic compared to some of them. I think that deserves a degree of respect. Now, don’t get me wrong, I don’t kiss ass and genuflect. I’ve been known to get pissy and commanding if one doesn’t hold its end of the bargain up but I don’t treat any entity I’ve evoked like a hired hand. That’s like treating the cashier at the grocery store like your slave. Someone providing a service isn’t your servant. You should treat them with respect while also being firm that you want X and Y done.
As to why they help, I’m sure there’s a variety of reasons. Some like to create mischief and downright terrible situations for shits and giggles (those are my faves). Some like to create love and “good” things and some even want to empower you so you (speaking generally) won’t be such a sad sack. I think it goes back to the idea that most like to influence situations on this plane. What’s the point in having power if you don’t use it?