Draco gestured towards a small decorative knife that sat next to the test tube. "I need your body to test the effects of the potion on a werewolf."

Teddy paused mid-way in another step backward. "So... no blood sacrifices?"

His Uncle tightened the handkerchief on his arm with his hand and teeth and then gave Teddy an annoyed look. "Why would I do that? Stop being difficult, Teddy. I need this for my experiment."

Teddy hesitated at the idea of slicing into his skin, especially at the sight of red bleeding through the handkerchief on Draco's arm. Still, it wasn't that much to ask for when it came to solving Lilith's murder. He sighed. "Can I heal it magically afterward?"

As Draco muttered his assent, Teddy rolled up his shorts so a long keloid scar across his thigh was visible. Teddy wasn't sure why the scar wouldn't heal. It probably had to do with the rite potion that had been poured into the cut during his initiation.

Teddy was about to cut into it when Draco grabbed his arm. "How did you get that?"

"That's where they cut me for the initiation ritual and magic can't heal it. I don't want another scar if I can help it." Teddy thought it was unlikely that he would get a scar this time around. But seeing he didn't know what Draco had planned, he didn't want to risk it.

Draco stared at it with his lips pressed thinly together. "I don't want my results screwed up by it either. Cut from somewhere else."

Teddy gritted his teeth for a moment and then gave in, switching to his other thigh at about the same spot. It was just high enough he could hide the scars even while wearing swimming trunks. He then copied what Draco had done earlier. When Teddy pulled out his wand to heal his leg, Draco motioned him backward.

"Do that by the door."

Teddy clamped a hand over his leg and backed up to the door. By the time he reached it, enough blood had slid through his fingers to soak the top of his sock. Trust his Uncle to make him feel imbalanced the second they started talking. Shaking his head, he healed his thigh and then Scourgify-ed his sock. By the time Teddy returned, Draco had poured the brown liquid over his own test tube and was casting spells on it and then scribbling on a notebook. As far as Teddy could tell, nothing had happened. When it looked like his Uncle was slowing down, Teddy asked, "Anything?"

Draco shook his head. "Possibly. Definite increase in the release of sympathetic hormones and imbalance of humors. Could it change a man to a wolf? That... too little to tell. What human would willingly be a test subject? Unlikely..."

"Uncle?"

Draco waved him off and poured the same brown potion on Teddy's test tube. The skin hissed and smoke drifted up into the air. The room was full of that burning and rust smell that had been present over both Lilith's and Hermione's wounds. But now the smell was not faint and instead came up in great billows with the smoke.

Teddy choked and covered his mouth with his shirt. "Uncle! That's horrible-"

"Shut it, Teddy," Draco said before starting into a series of spells again. This went on for some time, the skin completely black by the end of it. Then he picked up the white potion and poured it over the tube again. This time it steamed, letting off another horrid magical stench that somehow was familiar to Teddy.

It took Teddy a few moments to recognize that it was very similar to the prevailing scent in Hermione's hospital room. The smoke was soon thick enough he was having a hard time breathing. Teddy quickly covered his face again with his shirt. Slowly it dissipated enough that Teddy could see the vial again. The two potions had formed a dark shimmery mass that slid around his blackened piece of skin, more grey than black now .

Draco was back to casting spells and Teddy just focused on using his shirt as a filter for the air he was trying to breathe in. They were two weeks away from a full moon so his senses were dulled to almost human but still the stench was practically unbearable. Caught up in this, Teddy was a little slow on the uptake as his Uncle stormed over to him and grabbed his shirt collar.

"Fireplace. Now," Draco said as he half-dragged Teddy behind him.

"What? Where are we going? What happened?"

Draco ignored him as he threw floo powder into the fireplace. As it flashed green, he called out, "Grimmauld Place."

"Oh, hell no!" Teddy yelled, pulling on his shirt. "You can't tell him yet. I haven't-" Upon taking a full lungful of the tainted air, Teddy choked for several seconds.