Title: Don't Mess With A Snape

Rating: T

Summary: Severus Snape is the son of Hades and legacy of Hecate and proud of it. He's the only unknown survivor of an obscurus, holding it within him. When his actions causes Voldemort to target the Potter's he makes a choice. Why? Because the Potter's unknowingly adopted his daughter, Diana, and he's not going to allow any harm to come to her or Lily. The question is, will he survive unleashing the most destructive force of the whole Wizarding World. Crossover of Percy Jackson!

Disclaimer: I don't own any of Rowling or Riordan's characters and I'm making nothing from this.

Severus Snape knew, from the moment that he was claimed as a son of Hades, that he was different. A freak! To survive he suppressed his magic back home and he did it here. His grandmother, Lady Hecate, warned him of the dangers but he didn't listen. He wasn't going to be some kind of freak on show for everyone to look at. Deep inside him a force formed and he unleashed it.

Several people died due to his obscurus. It took Hecate, Hades, and Nyx to contain it and place it back inside Severus body. Only complete rage would unleash it and Hecate was sure that he wouldn't survive. Buffers were created to protect anyone, including the host, from this force. Several times Severus came close in releasing it, but the buffers held.

This was due to the bullying that he got from Potter and his friends. He hated them. They were just like his damn stepfather. He left Hogwarts and joined, to his father's horror, Voldemort. He turned his back on everything to work for the most vial wizard in a hundred years. The gods knew that it would only be a matter of time before Voldemort would come to the States, and kill their children. And so the gods made a choice, they would give him something that would unleash the force that they had worked to suppress.

And if it leveled the whole Wizarding world, that didn't matter anything to them.

When Severus found the child, delivered by the East Wind, he developed a connection. Her name was Diana and she was so cute and sweet. However, he couldn't keep her. So he went to Dumbledore and handed the child over to him, to give to the Potter's. Even though he hated James Potter he knew that they could give the child the life that he could never give her.

"Take care of her," Severus told Dumbledore.

"I will and I won't tell them who the father is," he promised and Severus vanished.

A couple of months later Severus overheard half the prophecy and went to tell Voldemort what he had heard. To his complete shock Voldemort, a month later, announced that he was going to go after the Potter's. No, his daughter would be killed, Lily would be killed.

"Master, please don't harm Lily or her daughter," Severus begged.

"And why would I do that. Two less Mudblood's to deal with," Voldemort said, grinning. "Trust me, you won't miss them."

Shock filled Severus body replaced by raw anger. The man that had promised to be around when he needed him was telling him that he was going to kill Lily and his daughter. Voldemort laughed at him and the anger rose within him. It rose like a wave and then the buffers broke as pure rage filled his body. He bellowed as his body vanished and his obscurus broke free, breaking through the walls and bringing the house down. He heard the screams of Death Eaters, but his focus was on Voldemort. What Severus had turned into was something that the moron didn't expect to happen. Voldemort managed to vanish and Severus followed him, the dark mark telling Severus where he was.

He heard people screaming, window shattering, Voldemort vanishing and Severus following suit. He wasn't going to get away with what he wanted to do. Voldemort crashed through something and Severus followed him. Suddenly the obscurus went back into his body and he saw that he was at the Ministry. Voldemort was looking at him with something close to fear.

"YOU USED ME, YOU USED EVERYONE. YOU DON'T BELIEVE IN ANYTHING BUT WHAT YOU BELIEVE. YOU DEFIED DEATH AND NOW YOU WANT TO KILL MY DAUGHTER AND LILY. I WAS A FOOL TO BELIEVE YOU, I SHOULD HAVE LISTENED TO MY FATHER. YOU DON'T CARE ANYTHING ABOUT ME, ABOUT MY PAIN, ABOUT OTHERS. AND I'M GOING TO BRING YOU DOWN."

The obscurus was forced out and it hit Voldemort full force. Severus didn't know what happened next as his world turned black.

"You did it, my son," a voice said, "However, he will be back and it won't be the Potter child that will defeat him once and for all. It will be you."

Severus was in a dream, in his father's throne room.

"I'm not dead," he said.

"Your close, but you will survive," he said. "The obscurus is for you to command without death. However, I'm disappointed that it took you so long to find out that Tom cares nothing for you. I care about you, your grandmother does, and not these mortal fools that wishes to use your talents. It's time for you to be your own demigod and not a puppet."

The words were stern and Severus knew that he had been waiting a long time to say them.

"Yes, father."

"You will have to go to their prison but he will be back. And when he does, you will have to face him."

He had mentioned this before, not that it made it much easier. Personally Severus couldn't understand how someone who had been killed by an obscurus could come back. It should be impossible.

"How can he come back from that?" Severus asked him.

"Because he created Horcrux's," his father said with disgust, "And since he didn't kill you then a piece didn't escape."

Severus felt like he was going to throw up. All children of Hades knew about Horcrux's.

"Dear gods," Severus said, "How many?"

"Five," he answered.

Oh he was so going back down.

"Stay hidden in the shadows," his father said, "Lady Hecate will make your stay in Azkaban comfortable and then your time to return to the world will take place."

"Yes, father," Severus said.

No matter how long he would remain in the shadows he would plan what he would do. And he would make Voldemort burn in the pits of Tarterus for what he had done. His daughter would look up to him as a hero and he would prove that not all Slytherin's were Death Eaters. Sometimes, they became heroes.

THE END

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A/N: I hope that you enjoyed this small one-shot. There will be a sequel to this story, where Severus finds out how true his father's words were and another one-shot where those that didn't die come after him. What a surprise they will get.