The more I look at Kallen, the more I feel her pain and frustration.
She was never really given a complete role in the world of Lelouch. She's not his Knight, comrade, partner, lover, friend, but a mixture of all of them. In a way, her question makes sense: What is Kallen to Lelouch? Is she just a replacement for what Lelouch doesn't have at the moment, or is she something altogether different?
Perhaps we'll get the answer in the final episode, and end this tragic relationship.