"Mm, finally," Kaiba answers carefully. "What happened was---it turned out he'd been so willing to adopt me because I resembled Noa, his biological son. My stepbrother had been fatally wounded when he was about twelve, so Gozaburo uploaded his brain into a computer...and he got so busy training me that he slowly forgot about Noa. But when I seized the company, he uploaded his own brain into the same computer and they hatched a plot for revenge."

This part is...actually important, but the details aren't, so he starts to speak a little faster.

"When we were on the blimp during Battle City, they launched their attack. Forcibly uploaded Mokuba and I into the computer, and they accidentally trapped Yugi and his friends too. Noa battled us, manipulated Mokuba, the Pharaoh had to save me yet again...turned out their plan was to eject one of their brains into my body so they could seize control of the company that way. When that failed, Gozaburo betrayed Noa and switched gears to launching nuclear strikes on the world's centers of government---Noa kept Gozaburo locked down and launched a strike on the computer to prevent that, so both their minds are gone."

It had been too much for Seto to process at the time. He'd coldly told Mokuba they needed to move on, but now...

"Gozaburo had treated Noa much more kindly than he'd ever treated Mokuba or I, but it was all a farce to control him in the end. Noa befriended Mokuba in there, and...he gave up his own chance at life to prevent Gozaburo from winning. He'd only been twelve, and he never got to truly live."

Kaiba squeezes the locket once more. "Living freely is something most people take for granted, but it's a gift. I don't want to waste it this time."