I've always thought wolves were one of the coolest animals around, but as I looked into Space Wolves I hated them as a chapter. Ever since I started
40k I've been looking for different approaches on wolf based armies, so I decided to use the Space Wolves codex for a lycan army and developed my own background for them.
Briefly put, these guys used to be Space Wolves and were subject to the experiment of chaos sorcerers. The experimentation left them half human half wolf and in constant pain. They sought the help of the Space Wolves they once called brothers, but were shunned by their fellow marines because their blood was tainted with the Thousand Sons' magic.
Now they surround themselves with wolves to feel a higher sense of belonging and to feel more human. They constantly face internal conflict because though killing is the only way to mitigate their pain they'd rather act civilized and keep peace to feel more human and less like monsters. The few that kept the most human qualities lead them to war to temporarily ease their constant suffering.
Now they separate themselves into two sects: those who strive to be accepted by the Space Wolves and those who live to hunt them to extinction.
I have some pictures here:
http://www.dakkadakka.com/gallery/images-44209-16881_Custom%20Space%20Wolf.html