Here's a snippet of dialogue between Mahoro and Ryuuga when they fight on the roof of an abandoned building.

Ryuuga: To attain something in the realm of sanctity, one must cast away all that is profane and secular. But sanctity and profanity are like twins. As one grows, there is always the shadow of the other looming alongside. To be obsessed with other people's hearts, but to not have any obsession within your own, that perhaps, is an impossible proposition. Coming here to observe you, I learned how difficult it is for us, the spirits born to fight, to live amongst humans.

Mahoro: I, I will never sacrifice something within my heart for some ulterior motive. Because that is the very product of this irrepressible thing we call obsession.

Ryuuga: Then... For you isn't serving Suguru a form of atonement to him and to his father?

Mahoro: Perhaps. At first, that was my intent. but now that is not the only reason. With Suguru-san, all his friends, and Shikijoh-sensei, I am happy to live my days as if I were human. As the housekeeping maid for the Misato family, as Andou Mahoro, I wish to continue living my life as I am now. For that... for none other than myself, I will fight.

Ryuuga: V1046-R Mahoro. Vesper's ultimate warrior. I have a hard time understanding that you risk your existence to pursue such a petty path.

Mahoro: I suppose that can't be helped. But, Ryuuga, I can understand the path you have chosen as I am a warrior like yourself. Understandably, it is inevitable path.

Ryuuga: Then... En guarde!