FINALLY FOUND SOME INSPARATION FOR THIS, HOPEFULLY I DIDN'T DO TOO MUCH OF A CRAPPY JOB :3
I based reader's transformation on Sonic's transformation into the werehog because when I played the game when I was a kid, I thought his transformation looked extremely painful, which seems realistic to me so enjoy :3
Your pov
What came next had to be the most awful pain yet, I couldn't even stay up so I fell on my hands and knees. I felt some of my bones cracking and rearranging and I felt something rip out of my back, causing me to scream in pain. But what came out of my mouth wasn't a scream at all, it was a dragon roar! I tried making other sounds but they just came out as dragon grunts, what is happening to me?!
I felt my ears disappear and night fury ears were on the top of my head, scales also appeared on the sides of my face and I couldn't see it but it felt like my eyes changed too.
Finally, my nails and teeth sharpened, which really hurt.
I let out one more scream of pain, but again it didn't sound human at all