Leo glared at Raph and Mikey. His fangs glistened in the light, and his crystal blue eyes were piercing. He hissed at his brothers, making them jump.
His youngest brother struck him first, heading for Leo's injured plastron. Leo could tell what Mikey was going to do, moving out of the way with ease. Mikey tried to knock Leo off his feet, the eldest brother jumped and kicked Mikey in the jaw, sending him flying backwards. Raph, now angry, attacked Leo with strikes from his sais. Leo just smirked and dodged every blow. He tripped his angry brother and grinned. Chains wove around Leo. He struggled, still shocked at the sudden attack. A tranquilizing dart hit his calf, he yelped and saw Donnie holding the chains and Sky holding the dart gun. He became dizzy, and his legs crumbled beneath him.
Not again! he groaned at himself. Then darkness took over his vision.

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Donnie dragged his unconscious brother back onto his desk where he was half an hour ago. Sky stroked his forehead.
"I feel so bad for him!" Sky sighed, "Imagine getting knocked out twice, and once was from your own brothers!"
Donnie understood what Sky meant, but if they didn't use the dart on Leo, he would have run away. He knew his brother to well. Raph and Mikey came into the lab groaning.
"Yeesh, Leo is so hard to take down!" Mikey grumbled.
"But guys! We have to treat him as an equal! He's no different to us, he just got bitten by an undead, blood sucking monster, that's all." Sky said. The turtles looked at her with a we-know-that look.
"Here are some books about vampires, read them while I test some of his DNA." Donnie handed out nonfiction books to the others.
Mikey groaned, "More reading?"
When no one answered, Mikey sighed and opened his book to read.
Raph read some facts about vampires:
Vampires are short tempered monsters. They suck blood of fellow animals and humans. But if one was to be bitten by a vampire, they do not become one instantly. They become 'fledglings' which are beginners. These are like pre-vampires who tend to be more humane than a real vampire. Fledglings need to drink real human blood before becoming 'full' vampire, fledglings survive on animal blood.
"I found something!" Raph said pointing at the thing he read. The others read it.
"So Leo won't go all full on us, right?" Mikey asked nervously.
"No, not necessarily." Donnie said as he went back to work on Leo's DNA. There was two more minutes of silence.
"You don't think Leo got bitten because of Livi's secret society, hitman thing, do you?" Sky asked anxiously.
Donnie shrugged and Raph looked away. Mikey started hugging his knees.
"Don't stress Mikey!" Sky said.
"Why not? The leader of our team is a vampire and now we are getting stalked by blood sucking monsters!" Mikey squabbled.
Donnie took the Leo's DNA and put it under his microscope. It had half vampire DNA, half human DNA, and half turtle DNA. He added more of his own blood and watched through the microscope a bit more. The human part of Leo's DNA vanished and the vampire part took over most of the turtle DNA. Donnie gasped.
"What happened?" Raph asked noticing his brother's distraught face.
"If Leo drinks our blood or human blood, then he will loose all his humanity!" Donnie exclaimed.
Mikey scratched his head, "Lose his what now?"
"He-will-not-know-us-and-go-all-crazy-and-kill-us." Donnie said slowly. Mikey nodded.
Leo started waking up. Everyone started panicking. Raph held up a piece of garlic pizza, which Mikey grabbed out of his hand and gladly ate.
"Mikey! That was my only defense!" Raph growled. Mikey smiled nervously.
"My bad...."
Leo's head throbbed, his limbs ached, but in a flash he felt better again. Thank you vampire instincts! He thought.
He felt everyone's glare on him. I'm not a monster, I'm not a monster, I'm not a monster. He chanted this in his head.
Expecting to feel chains, he felt nothing.
"Why am I not chained up?" Leo asked.
"Because we trust you not to go crazy on us." Raph said. He almost wanted to trust Leo. He looked normal, like his normal, ordinary self. But the vampire bite on his neck gave it all away.
"I'm soooooo hungry...." Leo grumbled closing his eyes, holding his stomach and bending over.
"So you can't eat pizza can you?" Mikey asked, almost crying. Leo loves pizza! He can't just give it all up! Mikey thought helplessly.
Leo looked at his youngest brother and shook his head. His brothers and Sky started looking, more, well, tasty. He licked his lips as his fangs slid out and his eyes changed to crystal blue. Wait! They trust you now! Don't go all crazy! Leo screamed at himself. His brothers and Sky started edging away from Leo, noticing his vampire look.
Leo looked back at them, "I'm so sorry..." He launched himself off the desk and straight towards them, hissing.