Omega Doctor (PJO/HOO/Dr Who)

Annabeth has been missing for 3 years and Percy is traumatized. He spends all of his time searching for her. When a mysterious person appears, claiming to be Chaos, creater of the universe, will he take up his offer?
Chaos promises to help Percy find Annabeth but only if Percy becomes the commander of his army and do a few special missions for him.

"Doctor! I thought they were just a myth!" Amy said in awe.

"But-But they're supposed to be extinct!" the Doctor furrowed his eyebrows in confusion.

"So are you, Doctor." the voice said the Doctor's name as if it was the funniest thing he had ever heard.

"And plus, how would you like to be called a myth!?" the voice questioned.

The duo whirled around only to meet two elegant twin swords aimed at their throats.

"He'll want to see you." the cloaked figure chuckled.