Kakashi had always had lone wolf tendencies, but then he was considered an oddball in his pack. The eccentric satellite, the one who left and came back without rhyme or reason, the one who could have been alpha if he'd wanted to bother, and responded to wariness and challenges with uncaring affability. Nevertheless, he was still a werewolf; he understood the pack, the support it could give even to those it didn't like. Kakashi hadn't been liked much as a cub; too strange, too enigmatic, too independent, and people who got too close tended to die on him; but he had still been home there.
He'd thought that Sasuke might fit there too; he'd probably never be well-liked, or accepted as dominant, even despite the boy's superior speed and natural weapons and his near-psychotic refusal to submit, but at least Sasuke would have a replacement not-quite-family.
He'd been wrong. Panthers didn't think like that. Panthers had people they liked and people they avoided; and most unlike his regretted uncle Obito, Sasuke didn't like lots of people. He certainly didn't like the she-wolves who flirted with him because he was mysterious, because his human body had a pretty face, and because dallying with him couldn't possibly have any lasting consequences of the squalling, defenseless kind. Sasuke didn't like being hounded for the sole reason that he was the ultimate safe crush; as for his teenage instincts, panthers didn't have much of a sex drive outside of mating season, and the she-wolves' pheromones had absolutely zero effect on him, anyway.
Kakashi was determined to be a good guardian, on the days he remembered, so he regularly left his old porn magazines in Sasuke's bedroom. Werecats or werewolves, boys were boys.
Sasuke had apparently decided to grow up to be nongendered. Oh well. Maybe it was for the best; dating humans never got very far -- and when it did, things invariably turned messy -- and it wasn't with a she-wolf that the brat would repopulate his pride.
Kakashi didn't really mind Sasuke's many, many differences, though; he got to be not-quite-father without having to take a mate -- most wolves didn't actually mate for life; trust Kakashi to be different once again, if only for conforming to silly romantic clichés -- and Sasuke was independent enough not to rob Kakashi of his own independence; and he was sleek and deadly and graceful, and never tripped over his too-large paws, and so hunting with the brat didn't hurt all that much.
Not that he missed Rin and Obito all that keenly, day after day -- it was more like the faint, easily ignored ache of an old wound; but neither did he especially feel like replacing them.
Sasuke was a good substitute; a presence in the apartment, but one that didn't sing and smile at him just because it was a nice day; and a hunting partner who reminded Kakashi a lot more of himself than of Sasuke's dead uncle.
Sometimes, he regretted that they were so alike; it meant that he was probably too panther-like inside to get any closer to the boy. At least Sasuke had the pack; he just had to reach out. However unlikely that was.
Kakashi had always been a lone wolf. Sasuke was learning that, too.