you and Aqua were wandering around the Realm of Darkness, as usual, but then you saw a person in a black coat, just sitting on a rock, looking at the dark sea, you two obviously approached, presented yourselves to him, talked to him for a bit, and all that, until he says something

Ansem: "...You remind me of a boy I once met. He's very much like you, true to his friends, and kind. This boy travels to many worlds, and fights to keep the light safe..."

Aqua: "Keep the light safe?... I've been away for so long... Are the worlds in danger?"

Ansem: "They nearly fell to darkness more than once... But at every turn, that boy arrived, with Keyblade in hand to save the day."

that makes Aqua curious, could it be her friends

Aqua: "Wait a minute! Is he called Terra!? Or Ventus!?"

Ansem just shakes his head negatively

Aqua: "Oh... Should've known... Well... What's his name, so?"

Ansem: "His name?... It's... Sora..."

Aqua gets even more surprised, you didn't, who's this Sora guy? Why he's important? But Aqua tears up a bit at hearing the name, so you think you should care

Aqua: "Sora..."