Euphemia and Nunnally
Euphemia and Nunnally probably get a long better than anyone else. Their kind and caring personalities radiate when with each other.
But of course, no relationship is so easy going. As well as friends and sisters, I would definitely call these two rivals as well. Rivals in love, that is.
When they were young, they would fight over who would marry Lelouch in their childish games. And as they got older, Nunnally is slightly jealous at Euphemia's relationship with Suzaku.
Of course, those are don't stop Nunnally from loving Euphemia, or from Euphemia loving Nunnally.
The sisters finally meet again in Stage 21, where Euphemia almost walks into the girl in a wheel chair. She apologises, and Nunnally is stunned, she immediately recognises her older sister's voice. They get to spend some time together, to catch up and laugh about the past.
When they part, Nunnally so wants to see Euphemia again. She requests something from Lelouch, if the can somehow see or talk to Euphemia again. There are few times where she asks something of Lelouch adamantly; she does her best not to be a hindrance to her brother, maybe asking to him to hold her hand when she goes to sleep. She goes on to tell him, that any way possible would be ok for her, as long as she could somehow see Euphemia again- phone, email, face-to-face, whatever. Anything was ok for Nunnally, as long as she could some how contact her older sister again.
And Euphemia, was ready to sacrifice so much for Nunnally. Part of her plans for the Special Administrative Zone for Japan, was for Nunnally. She planned to abdicate from her role as princess for Nunnally, even if that meant less contact with Cornelia.
Of course, after Stage 21, Nunnally and Euphemia never meet again. Euphemia's life is cut short and Area 11 is thrown into chaos. By the end of Code Geass's Season 1, Nunnally may not even know that the older sister she cherished so much is dead.
