I find it a touch silly that there are no evil leaning companions in the game, when there are companions that will leave you if your reputation stoops low enough.

I believe that there are only two humanoid companions that will not depart from you once your reputation becomes extremely low. It would have been nice to have the option for a companion that is for Caesars legion, or akin to some sort of raider type character.

raul, veronica, rex, ED-E and lily dont give a dilly who you kill

everybody else is for NCR

I had read somewhere that Veronica leaves if karma is low enough, although that may be incorrect. But regardless, this is a spoiler, but Veronica may be forced out of your group if siding with the Legion.

Raul is actually pro-Legion, if you talk to him. I doubt Lily knows who Caesar is, though, and Veronica will leave you if you wipe out the Brotherhood with her still a member, though she detests the Legion either way. So really, just Raul, who is still a pretty good guy.

The ideal new companion would probably be a cold and ruthless mercenary, with the personality of the woman in charge of the energy weapon shop in Freeside. Someone like that would fit our main character whether we're working for Mr. House or the Legion. In any case, I miss having a companion with a more smooth and urban style.

A companion pack DLC?
Would love it.

The humanoid companions in the game are mostly rather eccentric with a lean towards the "good" side. The two companions besides the obvious robots that you can complete the legion questline with both seem somewhat detached from the whole affair, especially the mutant. I think the game is in need of an evil or mercenary style companion.

Burned Man companion DLC. Make it happen, Obsidian!