To the doctors it's nothing short of a miracle that Seto Kaiba wakes from his coma so soon, relatively healthy and eager to begin work on other projects. To his servants it's a relief, freeing them up from 24-hour care; to his maid and close associates it's a cause for concern for him to be up and about so soon. Kaiba himself dismisses their concerns. All he wants is his little brother.

Mokuba Kaiba can scarcely believe it when he hears the news—his brother, healed from the Mind Crush after only a month, already asking for him by name. In an instant all thoughts of anything else are forgotten as he runs down the KaibaCorp hallways. He finds his brother in his office like he'd been gone for only an hour. Smiling, Seto turns from his work, rises, and offers a hug.

The hair is the same, as is the smile, so different from his usual knowing smirk. Nothing is different about the feel of the warm embrace Seto gives him, and for an instant Mokuba feels nothing is wrong at all.

"I missed you," he whispers, burying his head into his chest. "When Yugi gave you that Mind Crush I worried you'd never wake up, Seto! I promised to wait as long as it took for you to recover!"

"I know you did, and I'm sorry it turned out the way it did. But everything will be fine. Now that I'm awake, there's nothing that will stop me from getting my revenge on Yugi."

Mokuba blinks; while revenge had been on his mind, it wasn't a top priority. That could wait until Seto was alright. He pulls away, more out of surprise than anything, and notices something about his brother that he hadn't before.

There's a thin leather strap around his neck—almost like a noose. Something golden glints just under Seto's dress shirt, just enough for anyone far away to dismiss it and for Mokuba to pick up on it. Seto glances down, pulling up his shirt collar to hide it from view, but there's a hesitation to it, like he expected him to notice.

Then his brother meets his gaze, and there's a jolt like nothing Mokuba's felt.

The eyes are wrong.

Fear flashes across Mokuba's face and Seto's lips curl into a cold sneer.

It may look like his brother, and sound like him and speak like him, but whatever's there isn't Seto Kaiba. He instantly backs away.

"Mokuba," not-Seto says. "Is there something wrong?"

"Y...You...You're not..."

"I'm not your brother? Then who am I?"

Mokuba glares, fear quickly meshing with anger. "I don't know who you are and I don't care. I want you out of there!"

At that the thing in Kaiba's body laughs long and hard, a laugh that makes his skin crawl from how familiar it sounds. When the sound ceases not-Seto kneels to take Mokuba by the shoulders in a parody of a brotherly embrace. It's all he can do not to scream.

"Foolish boy. You know nothing of my power and even less of what I could do to you. If I wished I could seal your soul into one of those Capsule Monsters you love so much, and you'd be the empty shell while I continued unhindered. Or perhaps you'd like an up-close-and-personal look at your brother's new games."

Mokuba falters briefly, but is undeterred. Anything would be worth it to see Seto's smile again. "Do your worst."

Another laugh, this one closer to a cackle. "Oh, I think not. While I could destroy you, child, I'd much rather work with you."

Mokuba gives him a dead-eyed stare. "You hijack my brother's body and want me to work with you. Are you evil, or just insane?"

"Both and neither. As long as I reside in this body, I can access Seto's memories, his thoughts… what's left of his dreams."

Mokuba blinks, hoping feverishly for himself to be among them. As if reading his mind, not-Seto smirks.

"You are in there, Mokuba, but there's something even more important than you consuming his mind. Care to guess what?"

Mokuba thinks it over, thinks about what the thing inside his brother had said upon waking up, and lowers his head in defeat.

"…I get it now. Revenge on Yugi, right?"

"Indeed. And that, dear boy, is where our goals align. I, too, want revenge on the one who'd bested me before—and I daresay you do, too."

Mokuba can't keep himself from nodding, but he needs more information to go on. "Say I do join you. What's in it for you, and what can I hope to gain?"

Not-Seto grins, stretching his lips a bit too wide, the teeth a bit too sharp, for Kaiba's mouth. "You'd get your brother back and your revenge, for one. If you help me defeat Yugi, I will return Seto Kaiba unharmed. It wouldn't be too hard—all you'd have to do is walk him through a role-playing game and ensure he loses. As for game pieces… you do like Capsule Monsters, don't you?"

Against his better judgment Mokuba's eyes light up. "Y-yeah… I do…"

The thing in his brother's body smiles wide. "Then why not? Yugi would never see this coming. I have plans in place to guide three others here, put them under my thrall, and together we can all defeat Yugi Muto and put your brother's demons to rest. You and Seto can be a family again."

He offers a hand, and because the body is his brother's, the smile so genuine, Mokuba almost takes it.

But he stops. Considers.

Mokuba frowns. "This doesn't make sense. What do you need my brother's body for? If your goals align as nicely as you say, let him go and team up with him or something! What you're doing is like framing him, and I bet if I told Yugi what was up he'd know it was you."

The being sighs and leans back. "Is that a no, then?"

"No deal."

He blinks, and suddenly not-Seto has Mokuba's collar in his hand, twisting the fabric tight. "Unfortunately for you," he says, in Seto's voice, "this is an offer you can't refuse."

Mokuba recognizes the look in his eyes as the same current of madness the real Seto had at Death-T.

"Do you have any idea how much time I've invested into this scheme, looking for a host who couldn't fight back, whose purpose aligned with my own? I had to cajole the pertinent information out of Yugi, get my host to send you the Ring, and get one of your nitwit servants to place it on Kaiba's body. I won't have it slip away because of you, brat. Your brother's mind is as shattered as it was when Yugi first performed the Mind Crush, and I intend to keep it that way."

He rips open his shirt before Mokuba can blink, and he sees—

He sees a golden Ring with five prongs, all embedded in his brother's chest.

"I am Bakura," not-Seto sneers, "spirit of the Millennium Ring. This body isn't my proper host, you know. Were he to die, I would live on. Whether Seto Kaiba lives or dies is of no concern to me, but I'd imagine it would concern you quite a bit."

Mokuba is on his feet in an instant, fists clenched. "You can't hurt Seto! I won't let you!"

"That's right, Mokuba, you won't let me—or, rather, you'll give me no reason to hurt him. Your brother is my body, mind, and hostage," Bakura says with a laugh.

Slowly, Mokuba unclenches his fists. Bakura is right.

He has to give in.

Bakura stands, straightens, smooths out Kaiba's suit. "If I were you, little brother, I'd put on a smile and forget this ever happened. After all—"the Ring's prongs sink deeper—"you wouldn't want these to leave any marks."

"…I'll work with you," Mokuba says slowly, "but you have to promise to give Seto back, and not to hurt him in the meantime."

For Seto's sake, he has to play along, but the first chance he gets he's telling Yugi what happened. He can't tell him immediately, though. If he loses the first match, Bakura wouldn't expect him to try again—and that's when he'll let him know about the spirit of the Ring.

Bakura ruffles his hair and it takes all his self-control to not bite his fingers. "You have my word. Now let's dispense with this foolishness and get down to business, shall we?"

Maybe after all's said and done—maybe, just maybe—his brother will be okay. The thought is enough to get Mokuba to smile, or, at least, fake a convincing one.

"When do we start…big brother?"

"Soon, Mokuba. Everything I've worked for will all come down to this. It will be an all-or-nothing gamble, but I always play to win. And for Yugi and his friends, it will mean so much more than just losing a game."

He turns, faces Mokuba. Smirks.

"One final game, and Yugi Muto will be nothing but a bad memory. Losing equals death, after all."

Mokuba can barely repress his scream, for in that moment the Spirit of the Ring sounds exactly like Seto Kaiba.

Monster Capsule GB is a Japan-only GBC game that has Yami Bakura possess the Mind-Crushed Seto Kaiba after Death-T and Monster World, lure Yugi and his friends to his tower, trap them in RPG figurines, and task Mokuba and others with guarding them and playing tabletop RPGs to set them free. While Mokuba is supportive of 'Seto' at first, before you reach Kaiba he duels you with a weak team and tells Yugi something about what happened with Kaiba and the Ring since Death-T. Since I don't have a translation for exact details, this is my way of explaining both scenarios, as well as how Kaiba got the Ring to begin with.