[X] Negotiations
-[X] Concession B: You will be able to tell select people who you trust (Zao, Pearl, Moon) about the Infernals.
-[X] Concession I: Information on the overall state of the Reclamation, known projects, Infernal activities in the Realm (broad overview of Reclamation and potential threats it poses.)
-[X] Reciprocal exchange of services: Assistance with assassinations on a one-to-one basis, trade of unique services (Prophet of Seventeen Cycles/Sorcery), intelligence on threats to Creation, and other opportunities for mutual advancement to be considered by maintaining contact.
The argument for Information is fairly straightforward. Knowing what they are up to and about in the Realm will let us see what kind of threat their plans pose, if they in fact pose any threat in the short-to-medium term. It allows us to see if we can use Infernal actions or even cooperate with them to a limited extent to further our own plans. It also establishes a precedent for them passing on information about the Reclamation to Ulyssian. And if there is something we can help them with given a clean conscience we can use PoSC or some of Ulyssian's other unique capabilities to work out a trade of favors under the third agreement.
We want to get them cooperative. To look at Ulyssian as a valuable contact. To come to him to further their goals and agendas, at least as long as those goals don't conflict with his own or advance the release of the Yozis. As they get used to dealing with him, there will be more of a rapport, Ulyssian will start looking more like... well, if not a friend, then someone who can be trusted within the confines of his word and who provides them valuable services. So if things do start to go badly with the Yozis (and Ulyssian can probably provide some potent examples via Odyssial's memories) then we'll be in a good position to exploit that to get them to defect, or at least turn rogue.
And since we don't actually have anything in mind for Sorcery, may as well. I just put it in as a holding vote anyway since it seemed a little more flexible a concession than an assassination. We don't need anyone assassinated, yet (that we know of). And negotiating a deal for help killing Anys Syn later on is certainly a good reason to keep a line open to them in the overall approach.