Jason was stunned. So stunned that there were a good 3 seconds where he simply stood there, horrified. Then his Auror training kicked in. He scanned the room quickly and noticed a slight shuffle in the shadows.
"Colloportus!" Jason shouted, pointing his wand at the door. It slammed shut as the other 3 were on their way up the walk. Then Jason turned to face the murderer, who was no longer hiding in the shadows. Most of his body was obscured by a long black robe, but Jason could just make out two violet eyes staring back at him, burning with hatred.
There was a pause when the whole world seemed to stand still. Jason only had one focus. The scum that killed his friend's parents. The two of them burst into action simultaneously, flashes of lights springing from both their wands. Jason ducked out of the way just as the spell slammed into the wall behind him. His opponent, on the other hand, had parried Jason's spell with his wand. He pivoted and slashed his wand at Jason again. Jason blocked it with his own wand and the two continued to duel.
He's powerful, but inexperienced, Jason thought. Whenever Jason shot a spell of his own, his foe blocked with his wand. He never dodged, and only moved to get a better shot at Jason. I can use this.
Jason heard fists hammering on the front door, which was now behind his enemy's back. He needed to end this quickly. Jason dodged another blast from the villain's wand, then fired three jinxes off in rapid succession. While the cloaked figure blocked each with his wand, Jason rushed towards him. The assassin stumbled and Jason sent one final spell barreling into his chest. The fiend hurtled backwards, breaking the front door and falling on the ground at the feet of Wolfric, Holly, and May, all of whom had shocked expressions on their faces. Before they could react, the killer rolled to the side and leapt to his feet. He turned on his heel and with a sound like a gunshot vanished into the night.
"No!" shouted Jason.
"Jason, what-?" May started. She stopped when she saw the tears streaking down her husband's face. Jason forced himself to look Wolfric in the eyes.
"I'm so sorry."
Wolfric's eyes widened in fear, and he rushed into the house, with Holly just a second behind.
