I think you first need to shed those misconceptions that demons work in a ''souls for favors'' fashion, as it is not how they work.
The ''price'' of the demon isn't your soul, not even your lifeforce or a blood offering. They can do things for you, with extreme ease, and they won't ask anything of you. Do they have a hidden agenda for helping you?
Not all demons are the same but saying that demons have a hidden agenda for doing things that the conjurer asks for is like saying the wind has a hidden agenda for blowing.
A pact, is in essence an agreement, binding both entities to honor a kind of bargain and work towards a long-term goal or a set of goals. It is not ''I give my soul, and the demon does all the work''. You will still have to do in accordance with what happens with the demon. Which is why you make a pact for ascent, not just spiritual, but also material.
With that in mind, read the works of Daemonolatrist Stephanie Connolly, going by the pen name of S Connolly.
Demons are spirits. And like many can do. Much like all can. But remember they are a being. With a will and are not. Slaves so say thanks be mindful. Of them be nice but. Be careful never. Make one or any spirit. Mad okay and only give. Your name to a spirit you trust or. If it is part. Of the pack your name gives. Them power over you.
Now you asked for me by PM to clarify the points that I made in my previous point so let me explain it all here:
1. The demon is a spirit, and as such, belongs to a specific current, representing the darker side of nature. It's essentially not acting because it wants something from you like your soul or your energy. The reason they're willing to help us is to expand their influence on the physical plane. Through us they get to do things, as well as help some become demons, thus increasing their ranks. The mere act of helping you would in itself be enough for them on top of any offerings you may give, so their payment is far better than ''your soul'' or something.
2. A pact isn't an agreement in which they give you something and you give them something else. It's one that binds you both, to work together towards a common goal. The demon gives you the means to accomplish it(teaches you the rituals, gives you the energy, whatever you need, etc.). It's not separate agendas, but a mutual one. The fact that it's more of a project than a favor, is the reason why people should make pacts for ''bigger'' goals.