Vesper and his crew had run up acset of stairs, Mondo holding off the unaffected Monokumas with his minigun

Mondo: Yeah! I'm happy I stole this!

Vesper lead his crew to the vault exit, and as he was walking through himself, Junko and Mukuro jumped him.

Junko: Sorry! Can't have witnesses!

Vesper knocked out Mukuro with a left hook, and threw Junko into the stair guardrail, which collapsed but kept Junko suspended over the molten sea of gold.

Junko was laid on the fallen guardrail, the only thing keeping her from falling into the molten wealth below.

Junko: Well, looks like you got me.

I remained silent.

After a moment, she spoke again.

Junko: So what's it going to be Vespy? You gonna help little, defenseless me?

Junko lifted her skirt slightly to tempt me.

But I knew her tricks.

I reached out cautiously, lifting Junko up from the loose guardrail.

Junko: What a gentleman. You know, if you were more polite, I would let you-

Junko stopped suddenly.

Junko: Ow! What was that!

Junko held her side, which had a injection needle in it.

Junko: What did you inject me with Vespy? Was it your love juice?

This girl....

Vesper: You know what you're one crucial flaw is Junko?

Junko pulled the needle from her, examining it closely.

Junko: What?

Vesper: You're predictable.

Junko: Oh? How so sugar?

Vesper: I knew you and Mukoro were following me since day one, and that this entire heist was orchestrated by you.

A look of surprise came across Junko's face.

Junko: You're lying!

Vesper: Actually, for once, I'm not. I knew something was off before I even left the airport.

Junko: How!?

Vesper: It all started with the tip off I got from a source regarding this vault. It was obviously you.

Junko: How? I made sure I looked just like you're source!

Vesper: You did, but you sent the tip off to me directly, which isn't how any of my contacts in the Thiefnet reach me, as it is to easy to get caught by the authorities. So I was suspicious of who sent it, but I knew that the vault was real, and I was going to get into it, but from the moment I got off the plane, I was careful to notice if I was being followed.

The rest of the crew came up the stairs.

Junko: Wait. So you knew we were following you?

Vesper: Yes, you started when I recruited Kaz and Hiro from the garage, but I still didn't know who you two were.

Celestia: You could simply find their info in the academy records, we already have a backdoor in.

Vesper: But the academy only knows what these two want them to know, so I took a less legal approach. I learned who you were via your handprint.

Junko: I never touched you with my hands! Though I really wanted to touch you all over....

Vesper: Actually you did, the day I met Mondo.

Mondo: I remember that, you were eating a private lunch.

Vesper: And trying to lure one of them out, and needless to say, Junko took the bait.

Junko: I did?

Vesper: Of course you did, I knew that you would want to get close, to reassure yourself that your plan was working. And you did just that by "accidentally" running into me.

Junko: But I still didn't touch you!

Vesper: No, not me personally, but you did run your hand around my jacket.

Flashback
Junko ran her hand across the backside of my jacket as she whispered in my ear.

Junko: See you later tiger.

Junko skipped off, her short skirt giving me a fine view.

Vesper: You left your entire handprint on my jacket, so all I had to do was take the fabric you touched and have it analyzed in the Theftnet. It didn't take long for the results to come back, with your entire history, including your plans for the Monokuma droids.

Junko: You found the plans for my droids?

Vesper: Yes, you're personal computer was locked with a fingerprint scanner, so it was only a matter of waiting until late at night to sneak in.

Peko: But when did you sneak in?

Vesper: Shortly after we had our "discussion" in my dorm.

Peko blushed.

Peko: So that's why you weren't in bed when I woke up, but came back to your room later.

Vesper: Exactly.

Flashback
Peko: Where were you?

Vesper: Had to deal with some business.

Kaz: I think I'm following so far, but how did you hack the droids?

Vesper: By using the labtop I stole from the Togami Bank.

Mikan: T-The labtop? How?

Vesper: well, it isn't just a normal labtop, but a experimental military computer called the "Orochi" Computer.

Celestia: So that's why you took it.

Flashback
Celestia: What are you taking that labtop for?

Vesper: May have info on other banks.

Junko: But using a stupid military computer isn't enough to hack my droids! So how did you do it!?

Vesper: Easy, it was all with Chihiro's help.

Chihiro jumped up.

Chihiro: Me!? How!?

Vesper: You helped me on two fronts actually Chihiro, the first was at the warehouse when you gave me the hacking device.

Flashback
I noticed that Chihiro was preparing to destroy the hacking device.

Vesper: Hey Chihiro, can I have that?

Chihiro: Um....sure Vesper, but why?

Vesper: Never know when you might need it.

Chihiro: So you used my hacking device and the Orochi Computer to create a hack for the droids!

Vesper: Exactly.

Celestia: But to perform a hack of that size would require a huge amount of power, more than we have, where did you get the power.

Vesper: Through the Horus Eye.

Mondo: You mean that little cube?

Vesper: Yes, before we started the heist, I had already reprogrammed Chihiro's hacking device to disable the droids, all I needed was the Horus Eye, which I took from the inner sanctum along with the Thunder Blade.

Peko: But when did you transfer the power to the hacking device?

Vesper: When Junko had us surrounded.

Flashback
I still had the Horus Eye behind my back.

Junko: Alright Vespy, hand over the Horus Eye or you're main girl gets it!

Junko pushed her pistol into Peko's cheek.

Vesper: Don't hurt her! Here! Have it!

Kyoko: Vesper, no!

I threw the Horus Eye to Junko.

Peko: So you drained the Horus Eye while you had it hidden behind your back.

Vesper: Yes.

Chihiro: But wait, you said I helped you two times, when was the second?

Vesper: you helped me again with the psycheformer.

Mondo: The what?

Vesper: The serum Chihiro developed with the psychology club.

Flashback
Chihiro ran in eagerly

Chihiro: Vesper! Look what me and the psychology club made!

Chihiro held out a case with a single injector filled with a blue liquid.

Vesper: What is it?

Chihiro: We call it the Psycheformer! It can remove any negative emotions in the brain permanently!

Vesper: Wow! That's incredible!

Vesper: I knew that Chihiro and the psychology club were developing the Psycheformer, but needed more funding, so I gave Chihiro my share of the warehouse job.

Flashback
Chihiro looked at me nervously.

Chihiro: Hey Vesper? Why did I get a bigger cut than everyone else?

Vesper: Because you did the most work, you earned it.

Chihiro gave me a warm hug.

Chihiro: Thank you Vesper!

Vesper: Once Chihiro and the psychology club had the Psycheformer developed, I knew Chihiro would bring it to me to show me how the extra cut helped. So the only thing left to do was keep it somewhere safe.

Flashback
Vesper: If you want, you could keep it in the vault here.

Chihiro: Really? Thanks Vesper!

Vesper: With the Psycheformer safe, all I had to do was start the Ultimate Vault job to lure out you two.

Junko: Booooring! What does some little serum have to do with all this!?

Hiro: Yeah Vesper, why is it important?

Vesper: Because it is what I injected into Junko.

Junko looked at me surprised.

Junko: So what does it do!?

Vesper: It removes the mind's ability to feel any negative emotions....

Including despair.

Junko's once colorful face became drained of all color.

Junko: You mean....you took my ability....to feel despair?

Vesper: I had to, it was the only way to stop you for good.

Junko looked down.

Mikan: Are you ok? How do you feel?

Junko: Nothing....I don't feel anything....

I picked Junko up.

Vesper: I want you to remember this, all of it. Every moment you feel nothing, feel hollow, and in your most private moments, I want you your to remember the one man who beat you....

I leaned in to Junko's ear.

Vesper:....and set you free.

Junko and everyone around me looked confused.

Junko: W-What?

Vesper: I know how you feel Junko, I'm the same way honestly. I'm a thief because I get bored doing anything else.

Junko blushed lightly.

Junko: So you care about me?

Vesper: I want to help you, come with us.

Mukuro had just woken up from her unconscious state.

Junko: Okay, let's go with them Mukuro.

Mukuro looked confused.

Mukuro: If you trust them.

Junko and Mukuro joined the crew in their escape.