What do you think about this. When pups are born, they are all either light furred(white, silver, tan) or Dark furred(Black, gray, and darker brown shades). The wolves believe this signified if the pup was born of the moon (hostility and evil) or the sun (innocence and good). Pups stayed with the mothers until they were old enough to fend for themselves, then the Moon born pups were outcasted to a band of "evil" rougues known as the Moonpelts whom had a bitter rivalry with the Sunpelts. Sunpelts being the light furred wolves, who tended to be a bit arrogant with an attitude that they were better than the dark pelted wolves.
Here's where our story picks up. Two pups born to a couple of Sunpelts. One pup, out of the unlikely odds, is born Moonpelted. When the pups are approx. 6 months old, the darker furred pup is outcast from the group. The two pups remember each other, and our plot involves the two main characters struggling amongst their own packs, all the while attempting to reconnect with their banished sibling.