My main question is, can you make a one-on-one deal with a demon using the simple demons of the magic book?
An exemplary person summoned the astraoth and invited this spirit using the ritual 2 or 3 system. Is it possible to reach a lasting agreement by speaking in this spirit?
If you mean, can you make a pact using the summoning techniques in Gordon Winterfield’s book Demons of Magick, the answer is yes.
Gordon Winterfield states in his chapter on Full Evocation that an ongoing understanding, a pact of sorts, can be broached. I like to think of it as an alliance.
said results rarely come with full attribution method
i.e. does a demon have the power to refuse a treaty i.e., astaroth can refuse a covenant that binds one to another?
Yes, a spirit can refuse a pact. That is why a true pact requires communication. It is a two-way agreement.