Thinking about how Sora and everyone connected to his heart are all anomalies. They all take over someone’s life or role in the story.
Sora was never supposed to be the original key blade wielder, nor wield the key blade that he does, Riku was. But because of Riku’s fall to darkness, the key blade chose Sora to wield it instead.
Roxas was never supposed to exist in the first place. Sora died to release Kairi’s heart, and because of this Roxas was born. For sora to come back, Roxas would have to go back to him eventually, making him never his own individual. (He is but that’s not the point rn)
Same with Xion. She was created as a replica–a puppet. Xion was a backup key blade wielder made for the organization because they knew that Roxas would go back to Sora. Xion slowly absorbed both Sora’s memories and Roxas’s power, before realizing she had to return to Sora and give back his memories so he would wake back up.
And Ventus was never supposed to be a Dandelion or be in the BBS timeline. Because of the possession that darkness had over him, he killed Strelitzia and took over her place as a Dandelion. This all led to Ven ending up in the BBS timeline and falling right into Xenoharts palm to use in his plans to create the X-blade.
I cant imagine how it feels to know you were never supposed to be in the place you are in now. And the saddest thing about all of this is that none of them chose or planned on taking over someone’s life or role. They’re all a pawn in the story, whether they like it or not.