Harry Potter/Dragonball Z Crossover

Hogwarts has a new program for 18 year old beginners. If they have at least a tiny bit of magic in them, but not enought to get in when they were 11, they can go to Hogwarts to be taught the most basic spells.Gohan and Videl have been chosen for this new program, and they are both planning on attending. Chichi is very happy with this arrangement, because the Hogwarts 18 year ols program not only teaches magic, but extremely tough regular classes. Gohan and Videl have promised to come home for the holiday. They are both (havent admitted it yet of course) happy that they were both accepted, so they can go together. Right now, they are looking for seats on the Hogwarts Express.
"Gohan, all the compartements are full. Do you think we should ask the people inside this one if we can share?" asked Videl "Sure, they look friendly enough!" Gohan opened the door to the compartement, revealing a boy with jet black hair and a strange lightning bolt scar on his forehead, a boy with flaming red hair and freckles all over his face, and a girl with thick, curly brown hair.
"Excuse me," asked Videl, "but can we please share these seats with you? There's nowhere else to sit, "
The girl looked at them with interest, "Sure. May I ask, are you part of the new 18 year old program"
"Yes we are. And who are all of you?" asked Gohan, taking a seat Harry. Videl sat next to him.
"I'm Ron, "said the red curly haired boy, "that's Hermione, and that's Harry. You know, Harry Potter"
"I think I remember something about you," said Videl, "You're the only one that survived that evil wizard guy, Voldemort's attack. And now he's back to life right"
Gohan brightened, "How did you survive? What attack did he use? Was it powerful"
"Yes," spoke Hermione, "He uses the Avada Kadavra to kill you. It will kill you instantly. Now that he's back, Harry has to find a way to defeat him"
"He's a human right?"asked Gohan puzzled "Well he's a wizard,"replied Harry "He attacks with a wand of couse, right?" asked Videl "Then," asked Gohan very puzzled, "If he's a human, then he can't move that fast, can't you just dodge his attacks? I know! I'll defeat him for you"
"You can't defeat him! You don't even know any magic yet! Besides, Harry is the strongest one here!" exclaimed Hermione Videl seemed to be interested now, "It didn't take much to kill Wizard Babidi did it, Ya Gohan, why don't you try"
"Are you all crazy! What are you talking about? You can't defeat Voldemort! He's a very powerful evil wizard"
"Okay, Okay, you're right I can't fight him of course not, I'm human too heh heh," said Gohan hurriedly. He didn't want his new friends to think he was strange.
-
Hermione was bored. She hadn't played matchmaker in the longest time! But here in front of her, was Gohan and Videl! They obviously liked each other, it was so obvious. Maybe she could somehow get them together... The compartment door slid open, and an infamous blond head peeked through.
"Well Hello. Remember me?" said Malfoy, "Ah, it's some more mudbloods come to join you. These ones can't even do magic," Malfoy took out his wand, pointed it at Gohan, and muttered, "Expelliarmus"
A blast of red light shot out from Malfoy's wand and hit Gohan straight in the chest. Nothing happened. Everyone stared incredulously at Gohan.
"Um..why didn't that disarming spell work?"asked Hermione "Seems Malfoy's losing his magical touch..." smirked Ron Malfoy chuckled, "Hmph, this time you won't be so lucky"
Malfoy pointed his wand at Videl and said, "Expelliarmus"
This time the blast of light hit Videl, and she was knocked off her feet. Her body slammed into the window behind them, and she slumped to the ground, unconscious.
"MALFOY!" yelled Hermione, "You might have seriously hurt her"
And she wasn't the only mad one. Gohan was acting very strangely. He was making strange noises of anger, and his eyes were flickering turquoise. His hair changed from blond, to black, and then finally stayed on blond. A gold aura of light surrounded him. "I don't know who you are...but how dare you hurt Videl!" A small beam of light shot out from Gohan's outstretched palm and hit Malfoy.
The next they saw, Malfoy was struggling to get up, his clothing ripped, torn, and fried.
Gohan's saiyan side seemed to be attempting to take over as he yelled, "And Don't you dare ever touch my mate again bastard"
As soon as Malfoy left the room, Gohan rushed over to Videl who was being nursed by Hermione. Gohan had returned to his normal form, but all eyes were fixed on him.
"How..How did you...do that? What kind of spell was that?" asked Harry Gohan ignored him. He only had eyes for Videl. "Is...is she going to be all right?" he asked "Yes.She should wake up soon. It was only a disarming spell, the only reason she was knocked out was because she hit her head against the window." Hermione turned her eyes on Gohan, "But, why didn't that spell affect you?"she asked 'I guess saiyans are partially immune to magic," he thought "Um...just lucky I guess," he stammered Ron was still in shock.
"Hey, Gohan, that girl, Videl...you called her your 'mate'. What's that about"
Gohan seemed genuinly confused by this question.
"You know, I really have no idea!" he said Suddenly, Gohan turned his face to Videl in horror. He rushed to her side and grabbed her body away from Hermione. "VIDEL! VIDEL! NO!" he muttered.
"Um Gohan...what's wrong?" asked Harry Gohan turned towards Harry. His face was deadly pale. "Her ki...Her ki is dropping to dangerously low levels! I can hardly sense it anymore"
"Her...ki?" asked Harry, Ron, and Hermione But Gohan wasn't listening. He was cradling Videl's head in his strong arms.
"Videl...", he muttered softly, "Videl..please...don't die,"I love you" he whispered, soft enough that noone but him could hear...

"Gohan. She's not going to die. What's wrong with you! She just hit her head!" yelled Hermione. Why was Gohan acting like this? It was just a simple bump on the head...or was it?
"Ya, she was knocked out. When she wakes up we'll take her to see Madame Pomphry.Chill man," said Ron "You, you don't understand! Her ki..." said Gohan Suddenly, behind them in the compartement, a tall man with messy black hair wearing an orange gi appeared.
"Who..what...HOW?" gasped Hermione But Goku wasn't listening. He rushed over to Gohan and Videl. "I came as soon as I sensed her ki drop. What happened?" he asked Gohan rapidly explained the situation, but before Goku could react, Hermione cut in.
"I'M SICK OF YOU GOING ON ABOUT THINGS LIKE KI AND HOW VIDEL IS GOING TO DIE. I DON'T UNDERSTAND AND I WANT ANSWERS RIGHT NOW!" she yelled