"ONII-SAMA WHY DON'T YOU LOVE ME ANYMORE, THE GEASS IS SUPPOSED TO BE PERMANENT!"
And then Lelouch began thinking to himself. Wondering why he has always been such a raging siscon. Realizing that...wait...Nunally looks nothing like me, or our mother! Just what is she? Is she a memory plant, a spy like Rollo? Did he have my moves already planned out 10 years ago? FAAAAAAAAATHER!
And that's the story of how Lelouch finally fucked Kallen.