Chapter 4
Harry stared at the blue hedgehog. The blue hedgehog stared at the Emerald. And then the hedgehog grabbed the Emerald.
"Thanks kid," Sonic said, smirking, "gotta jet!" He tried to jump back out the window, but didn't quite make it.
"Expelliarmus!" shouted Ron, his broken wand working for once, and the hedgehog was knocked across the room, the Emerald flying from his gloved hand. Harry ran to catch it, but a blue blur got there first.
Sonic stood with the emerald, glaring at Ron and tapping his foot in anger. "That hurt, kid."
Ron tried the spell again. "Expelli-" he was sent flying when Sonic headbutted him at the speed of sound. Harry pulled his wand out, pointing it at the hedgehog, but he was gone. Running to the window, Harry couldn't see Sonic. But he could see what his obsession with the Emerald had hidden from him. Hogwarts was under siege. Robots of every shape and colour were attacking, all with only one similar feature; a small, egg-shaped backpack-like structure, which glowed and sizzled. Spells were being fired at the mechanical army from every window, but each flash of light bent to hit one of the packs. They were absorbing magic; it was how they could work in a place where nothing else mechanical could. Every so often, one would be overloaded, and explode, but there were too many for that to work for long. The only thing stopping the army from overwhelming the witches and wizards defending the castle was a small, red figure which ran through the robotic ranks, destroying everything in its path.
Sonic sped through the forest, heading for the faint glow of Tails' laptop screen. Behind him, a small army of Buzz Bombers and Caterkillers tried in vain to keep up with him. He reached his little friend, yelling, "HiTailshere'stheemeraldbadnikscomingbyeTails!" He grabbed a tree branch, swung himself around, and sped off again, quite literally through several Badniks. Tails sighed, put the Emerald in a special case with the other five, and grabbed a large bag. He rummaged around in it for a while, and then pulled out a gun bigger than he was. "Time to go, I guess." He followed his hero, mentor, and friend towards the castle.
As Harry watched, a blue blur – the hedgehog who had just stolen his emerald – joined the fight for the castle. As he watched, it went straight through a whole line of mole-like robots, setting off a chain of explosions which destroyed several more. Then Sonic leapt into the air, using the wasp-things as landing pads, and then leaping onto the next one before they exploded. He reached the tower where Harry was, landing on the stone next to the window. He smiled at Harry before leaping off the tower, rolling into a ball and spinning. As he watched the blue ball of death spin towards the robots again, Harry looked down at the still-unconcious Ron. "Looks like you got off easy." He muttered.
Elsewhere, far from Hogwarts, Robotnik sat in front of a computer screen, watching his army get ripped to shreds. "Chaos Emerald not found," a robotic voice chirped cheerily. "Casualties at 60...70..."
As he watched the last few robots get destroyed, his face began to redden with rage. An overwhelming urge to destroy something rose up in his chest as he screamed, "I HATE THAT HEDGEHOOOOOOOOOOOOOOOOOOG!"
THE END.
PS: Anyone who cares to try can suggest a new project for me, but if no-one does then I'll either do a Doctor Who/Stargate SG-1 crossover (guaranteed no Timelords), or an alternate retelling of Star Wars, set roughly at the end of Episode 3, running to maybe around when Episode 4 starts.