Fallen King has a lot of awesome moments, especially for a one shot fic.
Pegasus's defeat of Yugi and Yami Yugi.
Joey grabbing the Millennium Puzzle before Pegasus can.
Yami Bakura helping the others out of the illusion.
Joey asking for the real Ryou to return once Yami Bakura corners them; when the spirit obliges, Joey punches him and throws the Ring away.
Tristan then remarks that he did that before.
Joey calling Pegasus out on why he'll never be as good a duelist as Yugi.
Pegasus responds by talking about how Kaiba mastered the game, then adds that he beat him too.
Tea telling Yami Bakura to use the Swords of Revealing Light to stop Pegasus's guards instead of the Man-Eater Bug.
Pegasus summoning Relinquished into the real world, causing everyone to panic, even Yami Bakura.
Joey summoning the Red-Eyes Black Dragon into reality with the help of the Millennium Puzzle and his own willpower, canceling out Pegasus's summoning of Relinquished at the same time.
Joey setting up a decoy Puzzle to fool Croquet.
Pegasus's ultimate plan for reality and his Duelist Empire.
Tristan suddenly remembering Kaiba's helicopter, then deciding he'll pilot it home.
Mind-controlled Tea summoning the Dark Magician and beating up Tristan.
Tristan searching through Joey's deck—while a mind-controlled Tea is firing magic at them—and finding cards to represent their friendship. When Tea blasts at them again, she finds two Armed Battle Guards protecting Joey and Tristan, and the Change of Heart that was used on her wears off.
Tea finding the key to the helicopter.
The heroes escaping Pegasus and Bakura while carrying the soulless Mokuba.
As dark as it is, Joey throwing Ryou off of the helicopter, ensuring that with his death the spirit can never go after them.