They’ve agreed. We’re at peace for the first time in millenia. However, now comes the difficult part. I… can go the Abyss, but I need to have Tethys give me permission, and guarantees that she won’t just try to assassinate me. I need to learn more about the kelpies or else this ceasefire will be for naught.

The trick would be offering something to the kelpies innocuous for us, but seemingly valuable to them.