Bishmon said:
Maybe not 'all fiendish all the time', but I'm not sure there's a lot of hope that it won't be 'all dark all the time'. I suppose, as others have speculated, the feral could be referencing fey, but if that's true, it's not certain those powers would come from anything other than the more sinister fey. 'Feral' doesn't exactly conjure up images of butterflies and pixies, you know?
No more than the Druid using their wildshape for dire bears and crocodiles, instead of wildshaping into bunnies and squirrels.
Feral brings to mind primal forces, primitive mental drives. The barbarian is more feral than the fighter, due to his raging ways. I would classify the Shifters from Eberron as more "feral".
In general, I prefer the dark sounding stuff. Because I would have to roll my eyes every time I casted "Embrace of the Rainbow Farting Unicorn". But, because I hate the names of Psionic powers and their over-abundance on new agey crystals and parapsychology verbage, I understand what you're saying.
None of the other people on your list play well with others. It may be fun to read about them, but they make bad team-mates. I don't allow evil PC's because they're bad for group cohesion.
Wolverine isn't necessarily anti-team. He goes off on his own, sure, but he's not adverse to teamwork. Batman often has a partner, and has always been a member of the Justice League.
Anti-Heroes can play well with others. Loyalty or protectiveness to a choice few while ruthless to everyone else comes to mind.
But ultimately, it depends on your game. If all your adventure is is just "Go in there to get the treasure" or "Go kill the dragon" with no personal hook keyed to the PCs, then it doesn't matter who or what they are. And if one of your players makes characters that doesn't play well with others, then that's
the player's problem. D&D is a group game, and he has to have a reason to stick with the group. Being dark doesn't preclude that.