I disagree, she has no development really, mystery only goes so far. C.Viper has a dynamic She is well.....Mom. And not just in the literally way if you hear C.Viper talk to everyone she beats in SF4 she lectures them, and not the usual philosophical fighter mess. She is actually wondering what the people are doing with their lives, the younger fighters in particular. She sees fighting as a job and she is questioning of their life choices. Not out of cruelty, she just wants them to do better. Sure she can taunt people at the end of the she sees most conflict as a hassle and seems upset she has to do this for a living. But for reasons mostly left unexplained, she gotta do what she gotta do to make that paper, help the world, and provide for her daughter.
Rouge is just some mystery lady who likes jewels and is sometimes nice to the red one, and is really nice to the black one, and is friends with the pink and purple one. I dunno she has nothing going on, hell a lot of her motivation is shadow or something in the moment. What I mean by c.viper is not literally becoming c.viper, it is becoming is not relying on a pseudo boyfriend to create her story. More solo adventures, maybe more delving into gun. Would be an interesting series of comic books.
C.Viper has a dynamic, she is the Street fighter Mama. Rouge kinda has traits, sometimes.