Hillwood Heroes is an Ultima Hey Arnold/Kingdom Hearts crossover story written by NickTheUltimaSwordWielder.
The story begins with Arnold in his room until Vanitas suddenly arrives threatening him about an invasion. Arnold seems intimidated by Vanitas' threat, but from out of a drawer, he pulls out a laser gun and points it at Vanitas' face claiming he know all about him from the Society. As Vanitas leaves, Arnold calls his friends Gerald, Helga, Harold, Stinky, Sid, Phoebe, Rhonda, Nadine, Eugene, Curly, Sheena, and Lila over to his house to tell them about the upcoming danger to their town. Arnold friends are less than enthusiastic about the idea and decide they want out. But Arnold reminds them of the day they first learned about the Society as they cut to a flashback. It was a few weeks ago when a shooting star crashed into their school. It turns out the shooting star was actually Mickey Mouse who looked beaten up as though he was in a fight. Before they could learn more about Mickey, the school bell rings and they run inside. When school ends, Mickey is gone, but he left a note for the others to read along with a piece of the Star Shard which Mickey used to transport to different worlds. After a short speech, the kids decide they do want to help out as a shadowy figure watches over them. Curly however disappears screaming wildly and running down the street with two swords in each hand.
After arming themselves with weapons provided by the Society Scientists, the kids make their way to the FutureTech Industries building where they believe Vanitas and Mr. Scheck may be working together in. But through an incident with an exploding gun. Eugene hurts himself. Sheena and Lila stay behind to check up on him as well. Once the kids make it inside the building, a series events follow which involves Arnold and Gerald talking to each other about why they're in this mess, Phoebe, Stinky, Sid, and Nadine being captured by the Unversed, Helga staying outside while waiting for Phoebe, Rhonda getting used to fighting, and Harold being afraid of the Unversed. As Arnold and Gerald make it to the front door of Schecks office, a giant Unversed stands in their way. But Helga steps up and helps them out. It is also revealed that Brainy followed Helga inside (mostly to be used as a distraction). When they burst in, they confront Scheck and prepare to fight. But they realize that four of their friends were captured with the inclusion of Harold and Rhonda. Vanitas threatens to kill them all if they don't surrender on the spot. But Eugene arrives having recovered from his apparent injuries and frees the kids from their imprisonment. Brainy joins him and they try to teleport out of the building. But Vanitas launches a blue fireball at Eugene which struck just as they left. With their friends safe, Arnold, Gerald, and Helga prepare to hold nothing back. But Vanitas suddenly fuses with Scheck making them become one sentient being of darkness. Scheck/Vanitas destroys all of FutureTech Industries with Arnold, Gerald, and Helga still inside. Miraculously, they survived. But back at Arnold house, the kids mourn the apparent death of Eugene who had taken the ful force of the fireball launched by Vanitas.
Arnold runs down into Hillwood while Gerald and Helga try to catch up. But they are surrounded by a swarm of Unversed. While fighting, Curly appears and helps to fend the monsters off. The other kids arrive to help out too revealing that Eugene is going to die. They try to find Arnold who is pitched in a battle against Scheck/Vanitas. After being knocked out, the kids try to help only to be easily defeated. Arnold stands back up not willing to give up. A fireball forms in Scheck/Vanitas' keyblade and launches it at Arnold who becomes engulfed in it. But to everyones surprise, Arnold is unharmed and is now holding a keyblade which he uses to defeat Scheck/Vanitas. After the long battle, the other kids congratulate him. But Arnold finds the shadowy figure who has been spying on them from before revealed to be Mickey. He explains why Arnold has the keyblade, but also tells him that it's only temporary. As soon as Arnold figures out what powers it holds, he rushes to his house and uses the remaining power to revive Eugene. With Eugene okay and the town saved everything returns to normal. The story ends by cutting to two weeks later as there have been sightings of robots on Elk Island. Arnold and the gang suit up and prepare for battle.