My current Character has just finished the Soul Cairn area with Serana in tow. After having her tag along for quite a bit now, I have come to the conclusion she suffers from ADD.

During conversations of any length, she will move around, quite a lot. She will sit down and look at me. She walks from one side to another.

If I get within arm's reach of her, she almost always asks, "What can I do for you?"

If I mine ore, she'll walk right up to me and watch me as I mine, which is kind of funny watching her head and shoulders move up and down as I mine the ore.

If she is in my house and I am sorting/placing things, she is quick to go do an activity like alchemy or sit in a chair.

The overall picture she left me with was of almost constant motion and looking for something "to do." She seems to find it hard to just stand still