Seto was exhausted.
He was loath to leave his brother's doorway and head for his own bed though. Especially when he had been so close to losing the one person who mattered in this world.
Mokuba, thankfully, was fast asleep, drugged up on the painkillers their private physician had prescribed him when he had checked on the bullet wound in the younger Kaiba's right thigh, so he did not notice his older brother hovering, still unable to believe how badly he had failed his sibling over the course of Duelist Kingdom.
He wanted to blame Yugi. She and Oneesan had been the ones who had sent him into a coma after all.
But he could not.
They had done what they needed to do to protect their friends and family and if he was honest, he was better for it. Before they had shattered him and forced him to reassemble his soul, he had been a monster. A monster who had been willing to let his own little brother go insane or die for losing a game.
After all, defeat meant death.
Gozaburo had ensured Seto knew that better than anything, physically and verbally beating it and everything else he wanted to teach the young boy into the child every single day until the moment the younger Kaiba had finally defeated the old CEO at his own game and his adoptive father had committed suicide by throwing himself out of the 27th floor window of the Kaiba Corp tower.
Even Oneesan had helped towards that lesson. The 'Illusion of Death' penalty she had cast when he had cheated against her, had thrown him to his Duel Monsters and they had been furious at him for his behaviour.
He shuddered at the memory of the abused Duel Monsters tearing him limb from limb, even if it had entirely been within his mind.
Death-T had been as much about testing the Mutou sisters to destruction as it had been about revenge. After all, if they succeeded then he would lose, and it would not matter because Oneesan would destroy him and he would be gone. But if he won, then the Yugis were not strong enough to survive in this world and he was doing them a favour.
Including Yugi's friends had been a deliberate choice. He had believed that friendship made you weak and that relying on other people would get you killed in the end. By making sure that Jonouchi, Honda and Mazaki had been where they would jump to Mutou's aid and by seemingly biasing the games against the group, he had expected them all to fall apart and turn on each other, teaching the Mutou sisters that important lesson.
Instead they had found the clues that made the twisted, dark games fair and had forged their friendship into a potent weapon, creating a powerful connection that had combined with the Puzzle's magic to allow the 'tagalongs' to give Yugi and Oneesan the assistance they had required to defeat the Creator of Duel Monsters at his own game.
If he had not done that, if he had not given Doctor Mutou a heart attack and forced them to pull together, that connection would not have been there.
And if it had not been there, Duelist Kingdom would have ended very differently.
His hands balled into fists at the memory of how close he had come to losing his brother.
Crawford had backed him into a corner where either he had to break the island's rules and attack it's King, or he had to walk away.
And walking away was never an option.
By attacking Pegasus, he would have forfeited his own soul and been completely unable to help his brother but he would have done it on the off chance he could have taken the jerk down with him if it would help his brother.
After all, it had not been Yugi and her friends who had failed to protect Mokuba. It had been him.
He had been the one who had insisted on removing Mokuba from the protection of the group that had been looking after him, the one who had gone after Keith Howard, the one who had gotten his brother captured and shot…
And the one who had lost his chance to rescue him.
If Yugi had not spoken up when she had, if she had not risked her soul to get what everyone wanted, if Crawford had not been so desperate to get his hands on her Puzzle that he had agreed to her terms, Seto had no idea what he would have done in order to ensure he got a shot at defeating Pegasus and saving his brother.
Not that he had expected to lose to the 'little' Yugi. The weak, bullied pushover who had always hidden behind her friends when things went down.
He should have expected otherwise. After all it had been the little Yugi that had made it through stages one, two and three of Death-T, the little Yugi who had defeated an Eliminator despite the Shadows that had been trying to devour her, the little Yugi who would have been the one who taught the Spirit of the Puzzle how to play…
Then Yugi had nearly died while saving the souls that Crawford had stolen and getting the money Jonouchi had needed for his Imoto's operation.
Despite how much he had disliked her, he had felt her fade away just like the rest of her friends. Reassurance and guilt had surged through him, along with the sense of a light that felt warm, like the midday sun, before it had all slipped into nothingness, leaving a void behind.
A void that could have become permanent if the connection her friends had created during Death-T had not allowed them to protect Oneesan's mind from Pegasus's cheating and help Yugi cling to life.
He had tried lying to himself on the trip home. The bond would not have existed without him and as such, he owed Yugi nothing.
Except it had come about despite him, not because of him. Their friendship had grown stronger and shielded each other because they were fighting against him. He had not really aided in its creation.
As she had stumbled out of the helicopter and staggered towards the hospital, he had been forced to admit that he owed her more than he wanted to admit.
Between recovering his irreplaceable deck, protecting his brother, getting him into the tournament with help from Kujaku and saving his brother's soul, he had no idea how he was going to start repaying her.
Not that it mattered right now. He was too tired to deal with the issue and he had already promised that Kaiba Corp was going to pay for her Ojiisan's hospital bills.
A mumble from his brother's bed drew him out of his thoughts and brought his attention firmly back to his brother. He approached the bed quietly, checking that his brother was still asleep. When his brother's eyes were firmly closed he turned to leave, only for his brother to roll over and the shifting of the blanket caused something to fall with an odd twang sounding thud.
He stalked around it, only to pause, his eyes laying on the instrument that had hit the floor.
It was a guitar.
Specifically his guitar.
He had been learning to play before they had been surrendered to the orphanage by their relatives but when his aunt and uncle had wasted his inheritance, they had sold off almost everything he and Mokuba had owned, including the guitar his parents had bought him.
While he had been under Gozaburo's thumb music had not been allowed. It was a waste of time and money. Both of which could be spent in lessons on business or law or anything else related to Kaiba Corp. Even tapping his pen in time with a tune had been punishable with a beating for him, or worse, Mokuba.
The first thing he had done after their adoptive father's death that had not been Kaiba Corp related, was to go out and buy a guitar of the same make and similar model to the one that his parents had bought him.
Not that he had been able to play it since. There was always something to do for Kaiba Corp, be it the reshuffle, the games, the duels…
There was never time for music.
Wondering why the instrument was in his brother's room, he picked it up and quietly strummed, wincing slightly at the discordant sounds of off-tune strings.
It fit well. He felt off-tune.
He had always known what he was supposed to do and what people were to him. Now everything had been turned on his head and he did not entirely know where he stood or how he should play the game.
He retreated from his brother's room, mostly shutting the door behind him and headed for his own room, shedding his coat the moment he stepped through the door.
He slumped down onto his bed and started tuning the strings, working through it more to help himself unwind than because he planned to try and play something. After all the calluses that he had built up as a child were long gone and he had forgotten a good chunk of what he had learned.
"Seto?" His head snapped up at the call and found that his little brother was in the doorway, watching him with big, sleepy eyes.
"Hey Mokie." The older Kaiba put the instrument aside and went to stand up, only for the exhausted, semi-drugged child to clamber up onto the bed next to him and cuddle into his side in a way he had not been able to do in years. "Sorry if I woke you."
"S'okay." Mokuba mumbled as he settled in, his brother wrapping an arm around his shoulders, "You're gunna play?"
For a moment Seto was going to admit that he was not sure he remembered how but the hopeful expression on his brother's face made him pause and take a deep breath, "It's probably not going to be as good as before…"
"Can't be worse than my try." Mokuba muttered, eyes already beginning to close as his brother picked up the guitar and settled it, ready to play.
"Your…" Kaiba trailed off as he remembered the sound of off-key attempts at music occasionally reaching him as he tried to put himself back together. Music that, despite how bad it had sounded, had brought with it a sense of comfort and care. "I… I heard you. When I was trying to put myself back together. I couldn't respond, but I did hear you."
"Oneesan promised you'd come back to me when you were feeling better." Mokuba's voice was soft and slow, as if the boy was fighting to stay awake long enough to hear the first notes, "I figured that if I tried to play, like you used to before everything went wrong, it might help but… I'm really bad."
"It was out of tune. You'd probably do better now I've tuned it." The elder Kaiba reassured the younger, "I can try and teach you, if you like?"
"I'd rather hear you play." Mokie murmured as he progressively went limp against his brother's side.
With a slight chuckle Seto took that as the order it was and started strumming away, playing an old lullaby that had been one of the first songs he had ever learned to play. One that his father had taught him to help little baby Mokuba get to sleep.
It worked like a charm for the older child too as the younger Kaiba brother swiftly drifted back into sleep.
Seto continued to play softly, working through the library of songs he remembered and pleased to find that he had a better memory for it than he had realised, until he had played everything he knew that was not loud enough to wake his brother.
Once he was out of songs, he put the guitar down carefully on the end of the bed, where it would not fall and break and laid down carefully so he did not antagonise his brother's injured leg. Once he had settled, with his arms wrapped around the most important person in his life, he let exhaustion drag him off to dreamland. Happy, for now, that they were able to be together once again.
He could worry about the fallout from Duelist Kingdom and the Big Five in the morning.
Author Note: Inspired by some official artwork I found for Yu-Gi-Oh! Best Vocals! where Kaiba was playing on a guitar. It led me to wonder how Kaiba knew how to play and then the head cannon jumped in, so here you go.