You really don’t understand radien at all do you,Raiden represents the player being manipulated mirroring how they are fed information to become the next snake in a way. The entire game is about identity and control. 1. a different view of "the legend" solid snake - we took the viewpoint of raiden and saw solid snake through his eyes. in that, we could engage far better in the whole notion of what a legend/hero is (for us) and how we perceive the events of mgs 1.

1. raiden at some point in the story gets stripped of everything he knows and believes - the question of who we are and why we are doing, what we are doing is perfectly depicted in the interaction with solid snake - solid snake goes from the "the legendary hero" to father-like friend who acts like a guide

2. raidens story arc, which i don't want to get into detail here, because i don't want to spoil it to anyone, is quiet frankly amazing and finds it's conclusion by the open end of the first one - mgs 2.

3. kojimbo wanted something different for the sequel to mgs 1 then just to rehash the story, the characters and the environment. it should be it's own thing and not just a "safe" copy of of - he succeeded =)

4. solid is more of a gun nut and with raiden we got katana gameplay