Desdemona is an attempt to create some sort of demonic counterpart to the Great Beasts of the Weald Shamans
Just as the Weald's shamans create a Great Beast by layering the lives of spirit animals upon each other for several generations, so is the Bastard trying to do something similar by guiding the demon Desdemona through so many mortal lives, letting the imprint of their lives layer on top of each other in the same way to create something... more. To what end it's hard to say and how long that will take to achieve we can't know. But the end result will be... interesting.Desdemona is a being similar to the Bastard's father
The creation of the Bastard, as described in Paladin of Souls is a mighty demon fat with the lives of many men, who is selflessly granted a soul by a humble hermit. Sounds like Des is pretty close to that, doesn't it? All it would need is Penric to gift her, and they're close enough for that.The Father's gift to the Golden General (the spillover of which became the Curse of Chalion) was inspired by the Wealdean Hallow Kingship
Compare Ingrey's reaction to Horseriver once he is invested with the restored Hallow Kingship (and others' reaction to Ingrey once it lands on him) with the way Umegat describes his own reaction to the Golden General. Then consider that there are several centuries between The Hallowed Hunt and Fonsa's day, for the gods to think it over. Umegat's head groom is the lover he said was executed.
The man's older than he is, clearly his *present* lover, and missing his thumbs and tongue, which Umegat said had been removed. "A fine pair we make..." Cazaril survived at the end of Curse of Chalion by natural means.
The reason belly wounds kill in a medieval setting is infection. The lightning-bolt fire of the death demon leaving his tumor cauterized the wound—cauterization being a technology they haven't invented yet—preventing it from getting infected and letting him survive and recover.- The purpose of the "tumor" seems to have been to provide Cazaril with a spot where he can be safely stabbed. When the blade is removed, instead of a gush of blood there's just some clear liquid and a hint of blood. As nothing 'major' was hit inside of him, the usual infection risks are gone.
Penric is going to eventually meet either Caz or Ista
With the revelation at the end of "Demon Daughter" that he's now The Ageless, it's possible that Pen might survive to the era of The Curse of Chalion/Paladin of Souls. Which means Ista might get some high-powered assistance in her next adventure against the Roknari. Desdemona is the demon in Joen
The demon in Joen in Paladin of Souls is immense, old, and has a high tolerance for other demons. There's one other demon in the series this describes. The Penric novellas are set 150 years before The Curse of Chalion and Penric does not lead a safe life. Now, she has a daughter who is a temple demon and has human Roknari family. When Desdemona goes nuts, say, if one of her charges has a truly awful death, exactly how nuts do you think she'll go?