Mickey continued his way through the castle, taking down any Nobodies he saw in his way. He then found Diz, who reveals himself. 

Ansem the Wise

Ansem the Wise: It's been too long, my friend.

Mickey: Ansem the Wise. Why didn't you come to me before things got so bad?

Ansem the Wise: Xemnas, the Organization's Superior, is the Nobody of Xehanort, my foremost apprentice. The burden was mine to bear.

Mickey: Is that all?

Ansem stares at the moon. 

Ansem the Wise: I won't deny there was more. I was...obsessed with thoughts of revenge. My apprentices stole everything precious to me---my research, and my pride.

Mickey: I can't help you with revenge.

Ansem the Wise: I know. Riku's told me a thousand times.

Mickey: Where is he?

Ansem the Wise: He must be with his friends by now. Riku was a great help to me. I found him wandering the darkness, after you and he lost track of each other.

Mickey: Gosh, we didn't lose each other exactly. Riku left...well, 'cause Xehanort's Heartless was still inside his heart, troubling him. And he sure must've been suffering. But what I don't understand is why he looks like that now, when he's still Riku at heart...

Ansem the Wise: I am to blame. When I met Riku the first time he still had the appearance of a boy. Probably because he had such a strong heart. I asked him to find a young man named Roxas from Organization XIII, and bring him to me. When I told him it would help Sora awaken from his slumber, Riku left without a word. He fought Roxas. And I can only surmise Riku lost that fight. Riku must have realized then: to fight in the realm of darkness, he would have to immerse himself in that same darkness. And when he did...you saw what became of him. When Riku brought Roxas back to me, he was introducing himself...as Ansem. If that was what it took to awaken his friend, he was ready to live in darkness. Riku was the victim of my revenge. ...Oh, how my heart ached. I could only laugh to hide my shame.

Mickey: I guess it musta been after that when I saw Riku again. He said he wanted to help Sora...but he made me promise--- Promise that Sora wouldn't ever find out about what happened to him while he was out in the darkness.

Ansem the Wise: My friend, the time has come. I must make amends to these young people.

Back with you guys... 

(Y/N): GET LOST! 

You slash through the Heartless, only for them to be taken out by several shots! 

Ruby: Huh? 

???: Have you been Good Kids? 

(Y/N): ONE EYE! COME OUT! 

Xigbar then appeared. 

Xigbar: (Sigh) Roxas, you should know when to get your friends under control. 

Sora: Hey, my name is Sora! 

Xigbar: You've really put Organization XIII in a pickle. I guess that must be why the Keyblade chose you. But MAN, did it pick a dud this time. You don't look like you're half the heroes the others were.

(Y/N): What does that even mean? 

Yang: Don't listen to him, he's just rambling. 

Xigbar: As if. Right now, your time is up! 

Xigbar summons his arrowguns to his hands and leaps down. 

(Y/N): Bring it on! 

Xigbar: HA! 

He starts teleporting and firing his shots at you guys, though everyone still had good dodging speeds, and Ruby spun her scythe to knock them back at Xigbar! 

Then you guys attacked him as he was reloading. 

Xigbar: R for reload. 

He unleashed charged shots which you knocked back, and- 

Xigbar: Just try and dodge this! 

He began to manipulate the floor to his advantage, and then teleport everywhere to shoot you guys down! 

Blake: How fast is he? 

Weiss: This is crazy speed! 

(Y/N): WATCH IT! 

Xigbar: HA! 

He created portal holes and fired his shots through there to finish everyone off, only for- 

(Y/N): GOT YOU! 

You knocked one of his arrowguns out of his hands and stabbed him! 

Xigbar: AGH! 

He fell on one knee. 

Sora: Why do you guys keep calling me Roxas? 

Xigbar: Ha ha. Wouldn't you like to know? 

He then faded away. 

Sora: Wa- 

(Y/N): We don't have time for that. We need to get to Kairi now. 

Mickey and Ansem the Wise see Kairi and Ansem fighting the swarms of Heartless. 

Mickey: Uh-oh, they need our help.

Ansem the Wise: No. All the players are here. We can't interfere. 

Mickey: Gee, I wonder if Riku will ever change back...

Ansem the Wise: Riku chose that form so he could use the power of darkness. It won't be easy.

Meanwhile... 

Xemnas is on top of the castle offering millions of hearts to the moon! 

Xemnas: Yes...Kingdom Hearts... Rejoice, and feast on these hearts we offer! Shine your pale light on this empty realm... Share your power with all Nobodies!

Saix then appeared. 

Saix: Is Kingdom Hearts ready yet, Xemnas? 

Xemnas: Very soon.

Saix: Then shall I finish them off? 

Xemnas: Indeed. 

Saix smirked evilly. 

Saix: I've been waiting to hear that for a while now. 

Soon... 

You guys find Kairi!

Goofy: There she is! 

Donald: Kairi, you were great! 

Ruby: Hey girlfriend! How's it going? 

Kairi: Oh, hi you guys, I- 

Sora: Kairi, why are you here? 

Kairi: I wanted to come looking for you. I- 

(Y/N): Sorry you got into this mess. But I've been looking after Sora like I promised you. Trust me, i- 

She hugged you both! 

Kairi: Thank you. 

She also kissed you both on the cheeks. 

Kairi: This is real...

Blake: Wait ... is that- 

Weiss: ANSEM?! 

(Y/N): No, Xehanort's Heartless. 

He goes to leave, but- 

Sora: Wait! Ansem! I mean ... Xehanort's Heartless. 

Sora: I never thought for a second that I'd ever see YOU again. Just thinking about all the things you did makes me really mad. But... But you saved Kairi, right? I have to be grateful for that... Thanks.

Kairi: No Riku, don't leave. 

Everyone: RIKU?! 

Blake: How is that Riku? 

Yang: Yeah, it looks nothing like him! 

Ansem: I'm no one---just a castaway from the darkness.

Kairi: Sora, come with me. 

Kairi brought Sora over to Ansem and put their hands together. 

Kairi: Now close your eyes. 

Sora sees Riku in a black cloak. He is holding the hands of Sora and Kairi. Sora opens his eyes and realizes it! 

Sora: Riku... It's Riku.

(Y/N): REALLY?! WOAH! Riku, why do you look like- 

Goofy: He must have been helping us. 

Weiss: All those clues, they were from you? 

Riku: I was starting to worry you guys weren't ever gonna catch on. Sora never did pick the brightest friends.

Weiss, Yang, and Donald: HEY! WATCH IT! 

Sora: Why didn't you let me know you were okay?

Riku: I didn't want you to see me like this. I fought with Ansem. With...Xehanort's Heartless---when it invaded my heart, and I won. But to use the power of darkness, I had to become Ansem myself.

Kairi: Does that mean you can't change back? 

Riku: This battle isn't over. And until it is, I still need the power of darkness.

Ruby: Hey, look on the bright side! We're all here, and plus Kairi's wielding a Keyblade there! 

(Y/N): Yeah, we're all going to finish this together! 

Kairi: Exactly right! Well, Sora? 

Sora: Yeah! You're still Riku, no matter what! 

Riku just smiled. 

Back with Mickey and Ansem the Wise... 

The two make their way to a spot where the moon is in full view. 

Ansem the Wise: This spot should do.

He then set the device gone. 

Mickey: What's this gadget for?

Ansem the Wise: It's a device to reclaim Kingdom Hearts and encode it as data.

Mickey: Not sure I get it.

Ansem the Wise: I do not claim to know the outcome of this venture, either. After all...Hearts are unpredictable.