https://www.furaffinity.net/user/koekoek/

Copy-pasting (spellcheck does not like this but sticking to the original for better or worse) the story provided in the uploader comments here:

Auro was minding his own business when he was approached by Letia, who was looking for a new victim and the poor human male would do just fine, she started stripping him and pressed herself against him. In rhythmic motion she started stroking his shaft while she talked to him in a soft, hypnotic voice. "W-wait what are you doing?" Auro asked, fur starting to sprout on the spot she held his shoulder.

The fur spread quickly, acros the human male, mostly solid black with the exception of some glowing yellow patches on his shoulders "N-no let me go" Auro screamed, trying to break free, but Letia stood behind him and grabbed his chest, and started massaging him "Let you go? But you were starting to like this right?" hypnotizing her victim "N-no, I-I dont." Breasts started developing where Letia touched him "Oh? last time I asked you did." She smiled, the human skin on his shaft retreating into a sheath, the mind of the soon to be umbreon slowly changing. "i-it does feel good." Soon to fully sized breasts had appeared on the victim. "So you wan me to stop?" Letia asked one more time, and Auro shook hir head "N-no please dont, it feels so good~" as Letia moves her hand down to hir crotch for a final change.

As she touched the crotch just under hir balls she started rubbing and a vagina started forming under her touch "N-nya, wh-what are you doing" shi moaned "Making you whole" Letia grinned, the fur spreading to all of the former human, rounding up the changes. "Now..." Letia said with a grin, pushing her breasts against the new umbre "Why dont you repay me for granting your wish" The umbreon's tail wagged happily, hir mind having accepted the changes fully. Shi sat down with hir shaft ready and Letia wasted no time to sit on top, eagerly grinding her hips and squeezing the new umbreon's breasts. It didnt take long for the still sensitive umbreon to cum into her.

"Good girl"