In all actuality, there is an dominant female in the Greyback/Blood pack. Moira Crawford has been James' "female" for a long time now--he depersonalizes and only refers to her as his female--not that he's monogamous b/c he's not. Hitame has been using Moira as an NPC. (Moira was Hitame's but she was open in the possibility of reactivating her if it was helpful, at my last discussion of it)
I have not wanted to bring a steady female in for Fenrir at this age in his life, not that I couldn't. However, Moira's personality was strong enough that the pack didn't seem to need another.
James is a lot more animalistic, (a little twisted) and, at the same time, self centered. He has lost a lot of his humanity b/c he has no desire to own any of it and it has made him pretty brutal. He's also motivated by his own insatiable urge for power, including some weird desires for a lot more territory than Fenrir wants him to have. TBH, I think Fenrir's take on it is that being twisted is one thing but I think he sees James as being a bit too twisted for comfort.
Fenrir is bloodthirsty, you're right, but then he always was. In looking at him as an elderly character, I've tried to temper him, feeling that he might not be such a loose canon as James because, having lived as a werewolf for so many decades, he does not have quite the hunger as James does these days. However, he's not about to hand over running the pack to anyone else, and certainly not to James--someone that he knows he can't trust any farther than he can spit him.
I think your premise of a pack with a different bent would be a good one, Selwyn. Not every player wants a character who is really dark. I think a contrast of having a group of magical creatures that have the possibility of being good or neutral is a wonderful thing and has some great plotting potential.