Your uncle Sinfjǫtli serves as a grim reminder. He once stole golden wolf fur from a cursed noble, and donned it, transforming into a monstrosity wreaking havoc akin to the Ulfheðnar of legend. He had forgotten his fear and reverence of the golden wolves, and for that, he ended with the blood of many on his fangs. Though your uncle boasted the blood of the Allfather, no amount of absolution would grant his transgression the right to go unpunished. By no miracle will Sinfjǫtli, the ancient champion, ever reclaim his true human form...

Wolf's Portrait, Type-MOON Ace Vol. 15