Sonon is my favorite character. His demise made me ugly cry harder than Yuffie. His relationship with Yuffie is like a Big Brother caring for his sister. He was protective of Yuffie because she looks like Melphi, His dead sister. I was thinking maybe he is Yuffie's Uncle and Melphie is Yuffie's mom because they have close resemblance and by instrict Sonon became fatherly to a girl who he just met for a mission.
I know he got killed off because he was not in the original but his death made me cry.