I finished reading up on Tykis' Corrupt Path. Lots of good writing there. If I had to make notes, I'd say that 'elf', 'soft' and 'slut' were used a lot. Obviously he's an elf, but it was used a lot and by itself with no adjectives to spice it up.
I also noted that you gave very little love or attention to his horsey-tail. A shame. I assume it will be mostly unchanged, just turning black instead of brown, but still, prior to that, I think you only mentioned it once. I think you mentioned Kasyrra's tail more. Other than that, his ponytail was the tail most mentioned. I think in the nursing scenes, where he's on your lap, or the magical concoction drinking, where he's leaning back against you, would have been good spots for a single sentence about his horsey tail, either whipping you a bit, or draped over one of your thighs, or hiding his buns from your greedy eyes and forcing you to swat it aside.
I also noted that you seemed to forget the Secret, surprise Bad End, where if the Champ is at 100 corruption or even 99 on the last 'treatment', he comes his soul out into Tykis' mouth and it gets swallowed and Tykis turns you into his slave, spending the rest of your days with him sucking you off and getting filled with your seed. Tragic.
Other than that, as a demon, he should be obsessed with something ultimately. Demons are ultimately creatures of obsession. Most are obsessed with sex, or some with breeding, or some with dominance and dominating others, some making deals and haggling. Obviously it wouldn't work for him to be obsessed with sex (since your treatment technically brings him into control of his 'curse' or libido. So you should have something come up, something obsessive and driving for him. I would suggest maybe it be the Champ. They obsess about them (which makes sense), and desire their seed or milk or attention, especially since the Champ is probably one of the few creatures that broke their curse or allowed them to climax since Kasyrra cursed or enchanted him (or whatever is stopping him from reaching the big O. Just something to ponder.
Otherwise, it looks like a solid framework, guy stuff isn't for me, but I noted any typos or grammar issues I saw. Made a few notes or suggestions, which are ultimately just one person's notes and suggestions and others might feel differently.