Diane
"Zero that's... I'm sorry. I'm so sorry that all happened... I had wanted to help ease you into this so you wouldn't be overwhelmed or felt the pressure as bad... I wanted you to feel like you had a friend you could go to when things got tough. Someone who cared..."

*Oswald clenched his fist and took a deep breath.*

"Light or Dark, you're still a friend to me. I've used darkness before, and it is what has helped me survive so long in the Realm of Darkness. But... I must tell you something important. About the Door to Darkness and Pira. Something Master Mod didn't want me to talk about to avoid issues, but you deserve to know. Everyone deserved to know. I won't hide it any longer..."
Cindy
*The faintest smile dashes across Zero's face as Oswald accepts him. Here's an experienced, respectable, kind hero who's used darkness before and doesn't reject it. Maybe...*

*His thoughts are interrupted by Oswald's mention of the Door to Darkness. He raises an eyebrow, then slowly tenses up as Oswald builds up to the reveal.*

"Master Mod withheld a lot of information. To a fault." *He takes a breath.*

"Oswald, what do you need to tell me?"
Diane
"The Door to Darkness... Was my fault..."

*He pauses to let that sink in before continuing.*

"Pira was an excellent researcher and had wanted to do experiments on the Heart. At this time, willing volunteers had stepped up and we approved of the research as long as no one was hurt. Eventually, he discovered the Heartless... Created from the experiments, many people who had volunteered lost their life. This is where we had advised him to stop the experiments, which he agreed to. After a short time, he wanted to conduct experiments on the Heartless instead, but wanted a safer way to make them."

*Another pause.*

"He and I were good friends, and I have a power that no one else can use easily... I can create almost anything I need as if it were ink on paper or a canvas. So we made a deal that if I made him something to safely experiment on Heartless, then he would share as much data as possible on them so we would be prepared if they became a problem..."

"I created a door that would open up and let Heartless come through, but I messed it up, and created a door between our realm and theirs... I created the Door to Darkness and now all this is happening. After that, I vowed to never use that power again. It is too dangerous, and it could make things worse. I'm sorry, Zero... I'm no better than Maleficent or Pira. Just someone who spread darkness into the worlds..."
Cindy
*As Oswald exposes his greatest misdeed; the one that destroyed his world alongside so many others and set him on this fruitless quest, his facial expression darkens. This, technically, is all Oswald's fault. When he name drops Maleficent, though... Something snaps. And something else clicks.*

*He stands up from his chair, paces in a wide circle, then stops at Oswald's chair, looming directly over him. All his experiences, all his fucking failures. They've all been caused by this, and they've all led up to this. He grits his teeth and gives Oswald a scathing look.*

"You're. No. Maleficent."

*He exhales curtly through his nose, then begins pacing, talking all the while.*

"Pira, whatever the hell their hearts-damned pronouns are, fucked up. Experimented on the Heart, made a machine that turned test subjects into Heartless, and instead of stopping, decided to use that knowledge for something."

"If people could better understand Heartless, we could be better equipped to deal with them. Maybe we could even make a process to un-Heartlessify people. The logic's sound."

"So you fucked up. You gave Pira an unlimited source of darkness, and they went crazy and unleashed it upon the worlds. You think that makes you Maleficent? You think that makes you fucking *Pira*?"

"Maleficent separated Sunset from her loved ones, groomed her to become her mother figure, and talked her into murdering all of her friends. When she learned Sunset died, she called her a pawn and expressed no remorse. She went out of her way to harm and kill as many people as she possibly could, for no apparent reason other than her own enjoyment."

"Meanwhile, when you learned of your mistake, and of its sheer fucking magnitude, you know what you did? You did everything you fucking could, except, I assume, your amazing power."

*He turns to Oswald and slowly walks back over to him.*

"You're no supervillain, Oswald. You're just another fuck-up, like me."

"Now, we're gonna *Continue* Doing everything we can to fix *Both* Of our mistakes. We're gonna assess the situation in Agrabah to figure out how we can ensure knowledge of Keyblades doesn't spread. And we're gonna find some other way to seal the Door to Darkness. And if we can't do that, then we'll fucking conquer it, set up a fortified installation around it, and prevent it from ever being used again."

"It's not over. Don't give up." *He holds out a hand towards the Lucky Rabbit. His scowl, still present, is softened by the tears rolling down his cheeks.* "Not on your mistakes, and not on yourself."