It's still Velkyn, even if he looks different now.

He is currently torn between "I am still me," and "Can something like me ever be anything other than what I am...?"

Nature vs. Nurture and all that.

Well, hey, everything has its pros and cons.

On the cons, his soul itself is corrupted and infested by eldritch magics which will either destroy his free will itself, leaving him as a completely obedient, mindless servant of the very terror that destroyed him, or slowly seep away at the very essence of his heart, until all his feelings, hopes, and aspirations are slowly replaced by warped sadistic mockeries, turning him into a bloodthirsty fiend. Or some mix of both. Or some other, unexpected terror.

But, on the pros, no matter what happens it’ll be a good outcome for him in the long run! Either he saves himself and goes back to normal, or the corruption reaches the point where he accepts it, so he’s happy either way!

Plus, he looks like, super cute like this!

...I hope this joke isn’t annoying, haha.
It’s partly motivated by the fact it’s a little hard to sink in what those changes mean when he’s just so pretty. The horns, the glossy highlights on his skin, the extra eyes, the fangs just slightly poking out of beautiful lips.... even the fused-four-finger look is something I’ve never seen in a character design before and I adore it. I’m curious about what that pattern forming by his nose and eyes is, though. Something like a ridge in his skin? Maybe the start of an exoskeleton’s plates?

I’m betting on the four eyes and steadily simplifying claws meaning this is a spider-adjacent transformation by Lolth, although it could be something else still. I’d also love to hear what, if any, his symptoms have been besides the physical changes, and the nightmares you mentioned earlier. Does he remember said dreams? I’m curious about their content.

...I’m just curious about this story in general, although you’re under no obligation to tell us.

I admit, he still has all his fingers - they're just tangled up in his hair and around the new horns a little. XD But they are definitely claw-like, and there are definitely some big changes still in store for this guy. Potentially worth mentioning is that, while not shown, he is definitely abnormally tall at this point - currently standing at 6'10.6", and that doesn't include the new horns.

He still does have nightmares almost constantly. The only time he didn't was when he slept in a little pocket-dimension of sorts, which was proofed against things like Divination or other outside influences. Best sleep he's ever had in his life, but he can't stay there forever, sadly. He may not always remember the specifics of his nightmares, but much of the time, they are related to the ritual, to his kind (especially his old Master), or to the literal demons he has had to face (and still does). Interestingly, there is also a chance that he may be becoming something of an anchor point for people who sleep near him to start having unpleasant dreams of their own as well. It's not enough to be a hindrance, but it may be worth noting.

And there have been times when he's been absolutely vicious in combat. The party is justifiably terrified of him being turned on them instead - which has happened a couple times now, and he has nearly killed allies because of it. He is perhaps a tad more vulnerable to certain influences. This has led to the cleric now always making sure she has a specifically-labeled emergency scroll with her at all times, just in case - and it has come in handy once already. Little cleric gal is doing her best to help rehabilitate this creature that nearly murdered her when they first met. XD It's been slow progress...