Illia serves my Dragonborn at Heljarchen Hall, and she technically is supposed to be a good person.

Still, it's kinda funny when you think about it.

Who in their sane mind would invite a former member of a hagraven coven to move into their house?

What do you say, is it unwise to trust someone under those circumstances or is it reasonable enough given her attitude of rebelling against the coven?

I have Eola as my housecarl. She hangs out at Lakeview Manor with my wife and kids, keeping an eye on things. Necromancers like to set up shop near the road below the house now and then, so she keeps her plate full. Between the occasional bandits and sparse dawnguard-wannabes that attack now and then she has plenty to keep her satiated.

It also helps that I'm a vampire lord, so we have an understanding. Plus, my wife is turned so she keeps an eye out. Never can be too careful around cannibals.

I see no issue with Illia. If it makes sense for your character (assuming you RP to any extent) then have at it!

Come to think of it, I think I have Illia set as my Heljarchen Hall carl... or was it Windstad. Nope, Windstad is my laboratory. She keeps watch over my hoard in Heljarchen. All of the really dangerous relics that I come across are kept there. It wouldn't be prudent to leave Mehrune's Dagger laying around with children in the house after all, or Molag Bal's Mace out in the open when business guests come for supper. Never know what shenanigans those kids will get into.

Eola makes a wonderful stew, so I hear.