This story is a 'what if' tale, based upon the Yu-Gi-Oh! manga canon.
Honda stared the ceiling from the therapist's couch.
"Whenever you're ready Mister Honda."
Honda sighed deeply, bracing himself.
"It all started well over a year ago."
He heard the therapist stifle a small sigh. He could tell it meant she better make herself comfortable.
"My friend Yugi solved the Millennium Puzzle, an ancient artefact found by his grandfather in Egypt. It released this other side of him, who challenged people with darkness in their souls to what he called 'Shadow Games'. Whoever lost a Shadow Game would suffer a 'penalty'. One of those opponents was Seto Kaiba."
"The former golden child of the Kaiba Corporation?" Exclaimed the therapist.
"Yes the very same. After being defeated by Yugi so many times he forced him, me and our friends Jonouchi and Anzu to enter his theme park, Kaiba Land. There, we took part in a series of deadly games called 'Death-T'. In one of these games I was almost killed, but Kaiba's younger brother Mokuba saved me. From then on I felt like I owed him one."
"And how is all this relevant to the tragedy of almost two years ago?"
"Well, after Kaiba lost against Yugi in a round of the popular children's card game 'Duel Monsters', Yugi used the dark powers of his Millennium Puzzle to destroy the evil in Kaiba's heart. But this left him comatose, an empty shell for many months.
When Yugi and Jonouchi competed in the Duelist Kingdom tournament, we all met an imposter of Kaiba who used his Duel Monsters deck. Somehow this seemed to reawaken Kaiba and he made his way to Duelist Kingdom to free his brother. Mokuba had been captured by the host of Duelist Kingdom, Pegasus J. Crawford, as part of a scheme to take over Kaiba Corp.
Kaiba eventually confronted Pegasus only to find he'd removed Mokuba's soul from his body. His only hope of challenging Pegasus was to duel and defeat Yugi in a rematch. Although he tried his hardest Kaiba just couldn't win and when Yugi was one attack away from victory he took…desperate measures...
"Wait, do you mean…that was…"
"Yes. Kaiba was so determined to save his brother he stood on a ledge and threatened to jump if Yugi attacked and won the duel. I think all of us watching could tell Yugi was conflicted. But there was no doubt in my mind, or Anzu's or Jonouchi's, or even our other friend Bakura's that the Yugi we knew could never take a life…but the Yugi we knew wasn't in control."
"I don't understand."
"When I told you the Puzzle unleashed another side of Yugi, I meant it was as though another person stood before us. This 'other Yugi' seemed older, more confident and…more ruthless...
He declared his attack. I was sure, or at least I prayed, that he'd stop short of striking the finishing blow….But he didn't...
As Seto Kaiba's Life points fell to nothing so did he.
The next few moments changed everything."