==================MAKOTO PT. 1======================
Did you know that Makoto from Street Fighter could be a relative of Retsu? Although not confirmed by CAPCOM in anyway shape or form, both Retsu & Makoto share similarities in fighting. For example, both fighters don't use fireballs or "Hadou". Also both Makoto's background in Street Fighter 3: 3rd Strike is similar to Retsu's stage in the original Street Fighter.
Retsu's Stage -
http://www.youtube.com/watch?v=OXNQjwmJEZY
Makoto's Stage -
http://www.youtube.com/watch?v=so41H1AhGqE
Also Makoto's win quote against Ryu also give you a clue. Her win quote says; "My grandfather told me all about you. You really ARE strong." She could be referring to Retsu as Retsu himself fought against Ryu.
=====================C.VIPER========================
Did you know that C.Viper was originally planned for Street fighter 2? Early artwork of her was actually in Street Fighter 2. She was going to appear as one of the fighters but later was scraped for Chun-Li. Later in 2009, her design came right back & with some touch ups, she is know the C.Viper we love today. Also one of her concept art is now an official costume for her.
Her costume sketch & other Street Fighter Rejected designs/characters can be seen here ---->
http://www.youtube.com/watch?v=tsCN7bkvL_k
And while I'm at it, she could also be considered the based for Captain Commando, CAPCOM's former mascot. Here's a video showing you the similarities.
http://www.youtube.com/watch?v=gzsuSl6jcfQ
Many has speculated that was one of the main reasons why C.Viper was chosen over Captain Commando for Marvel vs Capcom 3.
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CAPCOM characters
CAPCOM characters 
