Mm. I like stories like the Exorcist, so I found myself nodding along with this one shot. I wonder if in the end, the priest gave it one last shot to resist, or to place himself entirely in God's hand. Does not appear to have worked, if that's the case.
The central problem with the story is the dumbass senior priest. For heaven's sake, you got the freshly printed priest with altered memories and an anger problem, and you let this charming demon get its hooks in him.... Father Merrin he is NOT. I suppose it's this thrown in desire to co-exist with demons - which isn't really supposed to be a thing, generally speaking, for Christianity, as the lines are very clearly drawn in the sand. That part of the story feels ill conceived at best.
Otherwise, there's all the makings of a good read here, and Ilya's facial expressions are quite beautiful to see.