Of course you don't understand. All I do, I do it to protect people. That's all.

[How could someone who joyfully heaped corpses to make a throne ever understand what it meant to be born to serve and protect, to guide and nurture? His existence itself was both proof of and a vessel for the Goddess' love--love she had somehow been completely unmoved by, in spite of being touched by it. He does what he was made for, because--simply because he was made to do so, perhaps. Or because he longed to help convey those sentiments to the humans who could no longer meet Her. Or because he wanted to make Her happy. Or maybe he'd simply inherited Her feelings himself. Humans are wonderful, terrible creatures, and whether they still deserve it or not--he wants to do right by them, even if it seems as though he and Flayn are the only ones left willing to carry out such work.]

I don't know why Rhea did what she did to you. I can't say I approve of it. But then, I can't say I know what tales Edelgard has been feeding you regarding her, either. If you can't understand why family would support each other.....