Just completed the Darklight Tower quest. At the end of the quest when Illia volunteers to be my bodyguard, I accept. I take her to my home in Breezehome and switch my bodyguard to Lydia [Lydia can always be found in my house in Breezehome since I've purchased all renovations]. I then see Illia walk out of the house and exit Whiterun. I thought this was bizarre because I thought she would take a seat in my home just like Lydia does when I dismiss her.

Question: Do I have to go back to Darklight Tower everytime I want to recruit Illia?