Yeah, Sephiroth is right.
I think he first realised it during their battle in KH2, when he saw all the faces of Sora's friends on his stained glass Awakening: Sora and his ability to connect to everyone is special. After that the rest of the battle was more of a test to make sure Sora was strong enough to feel good about conceding to. But you can tell he still isn't 100% happy about it. The look on his face when he says 'this could have been the other way around'. AHhh
Ahh Sora and Roxas....
Sidenote though, I don't think it's the 'newness' of Roxas heart that forms the obstacle here. In the ending AtW explains that it's just an innate ability of children to be able to see light in everything and give them hearts. And Sora saved Ven when he wasn't even properly born yet. Can't get much newer than that! So, I think it's entirely the attitude. And even though AtW says that, Sora's the only one who seems able to do what he does...
Great additional material to the topic, goldpanner. ^__^
Yep, that also goes well with the "I see, that's why [it choose you]"-bit Roxas mutters when floating above the awakening plattform.
The ability not only to
connect with nearly everyone but also apparently the ability to
revive/
recreate some of them (with a little help from Realm of Sleep powers + Ansem's data, further reinforcing the "together we can accomplish stuff") is indeed a very special power, and in my personal opinion also a very powerful one.
Who cares if Sora isn't a "true" Keyblade Wielder if he has such a kind of power.
Of course this comes with some disadvantages, as Ansem said that Sora needs to always follow his heart, which may lead him into traps sometimes like in DDD, but for that he has someone who looks out for him and will most likely make sure that Sora can use this reviving power of his without going down in the process himself, which is obviously Riku's designated role by now, as he even keeps one of the "ingredients" (the "manual") for using those powers right now entrusted by Ansem.
Of course Rox isn't happy about that, as he has to give up his existence after all. Yet I tend to believe that realizing the scope of Sora's connecting power (and his "general love for others", as Ansem put it), made his decision to at least accept the status quo for the time being easier.
I agree that you can somewhat hear out the bitterness in his words at first, the eventual brightening of his expression after Sora treats him as his own person though is so powerful because it is such a radical change from his attitude before. It's really somewhat cute, if I may say that, lol.
Now that you mention it I do think that is correct. I overlooked Sora's newborn heart being moved by Ventus' pain and spontanely deciding to help him, that's indeed a crucial and important point which serves to back up Ansem the Wise's analysis.
Roxas' attitude on the other hand is a certain degree more negative in general than Sora's and his personality was also developed in front of a total different and more malevolent background.
Many people tend to forget it because Roxas looks physically like 14/15, but his mind is actually way younger and more "malleable" so to say, like i.e. very small kids that can be teached and imprinted several things which will eventually shape their personalities.
Such "mental conditioning" and manipulating also served as a big point in Xemnas' and Xigbar's plans to convince the Nobodies to yield to the false facts they spread about their nature and capabilities.
Right now it really looks like Sora is the only one able to, but in accordance with the "Sora is just an ordinary boy"-mantra I don't think the ability itself is that rare or unique, it's only that Sora is the only one so far to actually bother to unlock that ability.
According to Ansem it has much to do with the mindset and being able to draw on the pureness of a child's viewpoints, which is something very few people are able to do and also
act upon.