Illia, the best (although bugged) follower.

Warning: Contains spoilers, for those of you whom have never been to [You must be registered and logged in to see this link.].

In the [You must be registered and logged in to see this link.] quest, you stumble upon a young woman named Illia whose mother is trying to perform a ritual to become a Hagraven and lead a band of witches. She employs you to help her bump off Mom before she can transform, as repentance for joining this evil cult.

Once you work your way through Darklight Tower and reach the top (an outside area), Illia uses you as a distraction, telling her she's brought you as a sacrifice to be used in her ritual. Then you both gang up on her and take her out. Once that's done, you have the option of taking her on as your follower.

I'm playing as my Khajiit character Chattus du-Fangue. He's a vampire, Listener of the Dark Brotherhood, Guild Master of the Thieves' Guild, a throat-cutting pickpocketing safecracking neck-biting... well, anyway, he's just 100% straight-up Bad News. Not really the best companion for a young lady who's regretfully had to kill her mother to save her from her own wickedness. But, since Mr. du-Fangue is indeed a ne'er-do-well, he decides to recruit her and bring her over to his own Dark Side.

One thing that seems to be overlooked too often about this character is the fact that she is one hell of a powerful mage! She has a devastating ice spike spell, and if you give her her dead mom's Staff of Hag, she'll use it -- 40 points of Force Lightning damage right there. Since she prefers ranged attacks, she'll stay back while you engage targets, so she doesn't get in the line of fire nearly as much as, say, Lydia.

I promptly gave her my full Nightingale armor set, a 40-point AoE flamethrower staff, the Staff of Hag, and a fortify magicka cloak. When a follower uses staves, as far as I know their charge doesn't deplete (similar to their never running out of arrows), so once you give them a staff, they can use it forever without needing to recharge it. Teamed up this way, we are now totally charging right through dungeons and blasting everything in our path. Despite declaring herself a force for good, she never complains when I totally murder people in cold blood right in front of her. She only seems to have a problem with trespassing, which is why I leave her outside when I burgle a house.

Only thing is, as a follower, Illia is bugged -- if you dismiss her, she will return in the general direction of Darklight Tower, and refuse to acknowledge you again, so you can't retake her as a follower. This is apparently true even after all the patches -- she's obviously far down on the priority list -- so the only way you can repair the problem is to use console commands if you're on the PC version. I didn't want to risk losing her, especially after I'd given her a lot of my gear, so I console-married her!

I actually haven't done that quest yet. I'll have to seek that one out!

When followers use staffs, they do use charges. I typically give my followers staffs because its good reliable damage, but I have to check their inventory and charge them up from time to time still. Also, if you give your follower empty soul gems and a weapon that sucks souls, they will charge your soul gems as well