no there is some relationship between all of them so ven or ventus is soras unbirth then as he went into a kind of sleep his heart went to sora thats why he can use a keyblade. cause ven was a original keyblade master then when sora turned into a heartless sora still had his heart so you guys know a heartless with a strong heart makes a nobody.so when roxas was forming a piece of ven and sora went into him and thats why he looks like ven and because he can use a keyblade. oh and slashed kite namine isnt a nobody well shes actually half witch half nobody thats why she looks like kairi and why xion looks like namine.and aussie roxas has emotions cause he has some of vens heart.