Disclaimer: I do not own Harry Potter or any ideas from that universe, that all belongs to J.K. Rowling. I do not own Justice League or anything from that universe either, that all belongs to DC Comics. I do own my OC, Sonja Taylor, though. I'm not making any money from this; it's just for fun.

A/N: This is my first story in a long time, so go easy on me. It's based after the events of Harry Potter and the Deathly Hallows. Original character from Harry Potter universe, other characters are from the Justice League animated series and Justice League Unlimited. Reviews are appreciated!

Chapter 1

Sonja Taylor swiftly deflected the curse aimed at her and shot back with one of her own. Although Harry Potter had defeated Voldemort some years ago, a number of Death Eaters were still on the loose and the Auror Department had had its hands full. As one of the newest recruits, Sonja hadn't been given many difficult tasks. That is, until she ran into Rudolphus Lestrange on a routine mission and captured him. She'd lost her left hand in the process, but had received a magical prosthetic and a commendation in return.

Now, she was dueling a Death Eater she had come upon while searching for an underground group of them the Auror Department had discovered. Hex after hex flew from each of their wands, most of them missing, the rest hitting shields they conjured. Sonja wasn't worried. In time, her opponent would tire and she'd take him down.

Something unexpected happened, though. Just as she deflected another curse and cast a Stunning Spell that hit its mark, a bright blue light surrounded her. She tried to cast a spell to make it dissipate, but nothing would work. Finally, she cast a Patronus Charm, hoping to at least send a message to her fellow Aurors before facing whatever dark fate was in store for her. The silvery panther sprang from her wand tip and raced off into the distance before the light surrounding her got brighter. A blinding flash lit the area around her; she was lifted off the ground a few feet and then collapsed in a heap.

Sonja could feel the magic in the room she found herself in. Pulling herself to her knees, she raised her wand swiftly, but too late. A spell she didn't recognize cast the wand from her fingertips, and she heard it clatter to the ground a few feet away. Suddenly, she could no longer move. Her eyes were fixed on a man, a sorcerer wearing a long blue tunic. A golden belt and matching gauntlets gave him a rather regal look. He held no wand, but the hand extended toward her seemed to emanate magic.

"So," the man muttered, a broad grin crossing his malicious features, "you can bring me greater power. You can bring me greater magic…."

Batman crouched on a roof overlooking the museum. The silent alarm he'd placed earlier that night had been tripped a few minutes earlier. However, he would let the perpetrator get away. If it was who he suspected—Felix Faust—he'd follow him back to his hideout and defeat him there. That way, he could collect the other artifacts Faust had stolen in the past few weeks.

After a few minutes, Batman spotted the sorcerer slipping through a back alley. He stood, readied his grapple, and followed him as he made his way through the city by way of alleys and shortcuts. Batman easily kept up. Soon, Faust stole into a rundown looking building. The Dark Knight slipped in through a second-floor window and followed his quarry into a dungeon-like basement.

"Soon, my dear, I shall no longer have need of you," Faust was saying, gathering together the numerous relics he had stolen. He seemed to be addressing someone in a far corner of the room, where the shadows were too deep for Batman to see anything. "Soon, I shall become the most powerful sorcerer of all time. I shall have the power to destroy my enemies and rule unhindered."

"Not likely, Faust." Batman stepped out from the shadows of the stairwell, batarang in hand.

"Ah, Batman. How good of you to drop in."

"Back away from the table, Faust. I'm taking you in and returning those artifacts."

"I don't think so."

He raised his hand toward Batman, and the latter just barely dodged a surge of magical energy that blasted a hole in the stairs. Batman threw his batarang, but Faust deflected it with a magical shield. The batarang knocked something metallic and hand-shaped off the table. Another batarang flew, this one slicing through Faust's arm before knocking something else from the table, something wooden. Batman heard whatever it was roll across the floor as he dodged another magical blast.

"You cannot win, Batman!" Faust shouted, smiling cruelly as one of his blasts hit Batman square in the chest. The Dark Knight fell to the ground, motionless. "I'm far more powerful than when you last faced me. And soon, I'll be so powerful that no one will be able to —"

"Stupefy!"

The voice had come from the shadows in the corner. A bolt of red light shot toward Faust's back, and he collapsed onto the floor, unconscious. Batman felt whatever spell Faust had put on him subside and climbed to his feet. Pulling a flashlight from his belt, he flipped it on and shined the beam into the corner.

The light fell on a young woman—she couldn't be any more than twenty-five years old. She had short dark hair that fell into her eyes, which were a brilliant silver. She looked thin, as if she had barely eaten in quite a while. Her left arm ended in a stump; her right hand held a carved, stained stick, which was pointed where Faust had been standing just a few moments earlier. She wore long black robes. Chains bound her right wrist and her ankles. Batman approached her swiftly, but stopped when she pointed the stick—weapon?—at him.

"Who…or what…are you?" she asked, her voice weak. He could still make out her British accent, though.

"A friend," he said simply. "If you allow me, I can free you."

After a slight hesitation, she lowered her hand. He stooped next to her and picked the locks on her restraints. Helping her to her feet, he did a rapid once-over to assess any visible wounds she might have.

"Are you injured?" he asked, noting that she was trembling.

"Only my pride," she answered, her eyes scanning the objects on the table and then moving to the floor. "Did you happen to see…oh, there it is."

She pointed the stick in her hand at the metallic hand that had dropped to the floor earlier. As if by magic, it lifted off the floor and attached itself to the stump on her left arm. She stumbled, but Batman steadied her.

"I'll get you to a hospital."

"No," she snapped suddenly, shaking her head. "Muggles won't be able to help me. I need to get home. I need a Healer."

Batman raised an eyebrow beneath his mask. "Did you just say 'Muggles'?"

"I appreciate your help, but I need to get home." She'd completely ignored his question. She pulled away from him and made for the stairs, but stumbled again. Batman caught her just before she hit the floor.

"I know a good doctor," he said, helping her back to her feet again. "At least let him take a look at you."

"Fine," she said with a sigh. "By the way…I'm Sonja Taylor."

"Batman."

"What kind of a name is 'Batman'?"

"Mine."