You and Kallen always close friends, and she subconsciously over time started to feel a new sort of emotion towards you. After a large scale battle, in which Zero was forced to retreat, you were thought to have been killed in battle, this broke her. But somehow, you come back just fine, and when you do, Kallen simply invites you to her room to "talk". As you entered, she wore her tight guren suit, and was laying on her bed silently. You approached, and she looked at you in silence, and relief.