Okay, HOLD on a second, you saying that just because Sora & Riku are friends, and that Sora's nobody (Roxas) & Axel are friends-that automatically makes Axel "Riku's" nobody?? Well, it's a good idea to think about for the moment, considering the whole "best-friend"-factor & the fact that Axel & Riku seem to act similarly in certain sitations..However, if you look closely you'll notice a few things:
#-Both Axel and Riku not only look completely different physically, but are very different in age (You may try to argue about this because both of their eyes are almost the exact same color, but notice the possible height difference, hair, facial features/attributes/etc)
#-Axel and Riku's main elements & weapons that they choose to weild do not tie to eachother whatsoever (Example: You have Axel who chooses to control fire on a flaming chakram, while Riku had wielded the "Soul Eater in CoM" & was seen brandishing the "Way to Dawn-keyblade (a mixture between Darkness & Light)"-in KH-2) +To further prove the differences, you have the fact that both Roxas & Sora had been wielding replicas of the exact same keyblades when you played as them in the game-meaning that in order for a whole being (Sora) & it's nobody (Roxas) to tie to one another, that they'll have to wield weapons and elements that trade back between one another (Oblivion=Darkness, Oathkeeper=Light) So in other words, do you think that "Darkness" & "Fire" relate/resemble to one another?
+I'm sure there will be other people in this thread that will also give you heavier differences between the two characters-some of them could be talking about examples in KH-1 & CoM. But that's my 2 cents of a description worth right now, I'll try to post a bit more on this later.