Riku was a great character. My eyes actually welled up a bit at the end.

Semi-Spoiler
Semi-Spoiler
Semi-Spoiler


He said to Sora, "Take care of her."

And in regards that he has a girls name, for one: His name is Riku, not Rikku. And secondly: Rikku's name is actually supposed to be Ryukku. Riku's name did not change from the original Japanese version.

This clears everything up.