A large, clear vat was sitting out on a workbench when they entered the lab. Harry glanced at it once, then looked away. He really didn't want to see the other Dark Marks his father had cut off his arm, time and again. They were blazing too, and tumbling over and over as the heat pouring from them caused the stasis potion to boil.
"You can see why it needs renewing," said Snape as he all but collapsed onto a stool.
"You can't do it beforehand so that the mark could be cut off as soon as Voldemort starts to call?" Harry flinched then. "Oh no. He's calling a meeting--"
"The Order's been informed. And no... the intricacies of the stasis potion require it to be renewed while the mark is burning, I'm afraid."
Harry almost said that that was lousy, but realised it wouldn't be a very helpful comment. He noticed his heart was racing as he wondered what horrible things Voldemort was going to do to Muggle-borns or half-bloods tonight. But there was nothing any of them could do about it.
I can't help them, he remembered Snape saying once in an angry voice.
So Harry didn't say anything about what horrible things the Death Eaters might do at their meeting tonight.
By then, Draco was already laying out potion ingredients in a neat row. One after another after another until there were dozens of them waiting to be used. Harry hurried off to throw on some clothes, then rushed back. Draco was still laying out ingredients.
"Why don't you start with the leaching the sap from these elm branches," he suggested.
Since Harry had never leached sap from anything before, he frowned. "Um...."
"Never mind, I'll do it."
"Harry, you could mash the ginger," said Snape.
"Finest pulp. Not a bit of fibrous material should remain," added Draco, already moving to deal with the branches.
Harry felt a bit like Draco was doing advanced mathematics while Harry had been set to practice his counting, but he told himself that Draco had made this several times before. And that Draco really liked brewing besides, so it stood to reason that the other boy would have far better skills.
He set to work pulping the ginger, his eyes more on Snape than on the pestle in his hand. "I understand you can't cut it off in advance, but now that we've started brewing...?"
"The stasis potion has to be ready to accept the mark," Snape answered, shaking his head. "Or Voldemort's magic will run wild." He gave a heavy sigh. "Believe me, Harry, I've experimented with every permutation. This one truly is the best."
Every permutation? Harry couldn't help but wonder about that as he finished pulping the ginger, and then, under Draco's direction began dividing it into twelve balls of perfectly equal size.
"Stir more rapidly, Draco," Snape advised from where he sat, looking like a rag someone had wrung out and tossed away.
"We have to do this right," Draco said, nodding as he moved the whisk around in a cauldron. "Because if we mess it up, we have to start over and Severus will have to wait through two brewing cycles instead of just one. And trust me, one takes long enough."
"I'll begin peeling the skin from the bat wings," announced Snape, pushing to his feet.
"I have it under control, Severus. You just slather on some more Lotion Potion and relax."
"Yeah," said Harry, remembering some things he'd heard on the telly. "Tensing up when you're in pain makes it worse, actually. So you have to try to relax your muscles. Breathe in through your nose, out through your mouth--"
"What a lot of Muggle rubbish," said Draco scornfully.
"Muggles do actually know some things worth knowing," retorted Harry.
"Ha."
Snape looked like he was gritting his teeth. Harry couldn't tell if it was with irritation at his sons or the terrible pain in his arm, but he decided he'd stop arguing with his brother.
"Lotion Potion," Draco insisted, laying his whisk aside. "This needs to set until it turns gummy, now, so I'll go get it for you."
"Yes, do. I believe my office door is standing open. And get your wand as well." Snape sighed as his fingers began to work with the bat wings Draco had laid out earlier. His hands were shaking, Harry noticed. He also noticed that Snape tried to hide that by turning his back slightly. "You'll need it later, for the charms. I... I don't feel my magic will be at its most precise."
Charms, Harry thought, something catching at his consciousness. Charms... charmed potions...
"Dad," he said when he'd chased that thought through to the end. "I was just thinking... what if I brewed some kind of charmed healing potion, and used a wanded charm to make it really powerful, and we tried using that on your wound after we cut the mark away? It might heal you up well enough that you don't have to go through this again."
Snape growled slightly. "It might also seek perfection to the point of banishing my arm into oblivion, you idiot child."
"Well, that's the thing about a potion," Harry countered. "We could test it first. On one of your crickets or something."
The Potions Master abruptly shoved his pile of bat wings aside and moved across the room to where Harry stood. "I appreciate the intended effort, Harry, but it appears to me that you are forgetting what happened just a few weeks ago in my class. Charmed potions are exceedingly temperamental, as you know. You only applied a hint of wanded magic that day, and still, disaster ensued."
"I know." Harry chewed on his lip. "But you said I shouldn't do unsupervised wanded magic. This would be supervised, right?"
Snape laughed slightly at that, even despite the pain he must be in. "You think I don't supervise my classes? This is fascinating."
"No, I meant that you weren't looking out specifically for wanded magic that day. But today, you would be."
"Today I'm in no shape to competently supervise anything, Harry."
"But--"
"That's quite enough!" Snape barked, frustration creasing his forehead. "You must restrain this saving-people thing, Harry. I've dealt with this odious mark several times without your aid, you realise. To have you insist now that you and you alone can end my torment is frankly ridiculous. I am coping, is that clear?"
Harry took a step back, understanding then that he'd somehow managed to offend his father. "I just wanted to help," he tried to explain. "I didn't mean you needed it. But..." His stomach churned with frustration. "I mean, why suffer if you don't have to?"
"Because experimenting with wanded powers is inherently dangerous. I thought you knew that, after the essay I set you."
"I do, but I'm pretty much fated to be danger anyway--"
Snape settled his hands on Harry's shoulders, but not in anger. His fingers squeezed briefly, imparting reassurance. And love. "There's no need to court danger, you idiot child. You will encounter perils enough without such reckless seeking after them, I suspect."
"It's worth it if it helps you--"
"No, it is not." Snape turned away as Draco came into the lab. Taking the Lotion Potion, he spread a thick layer of it on his burning mark. Steam rose up; Snape inhaled it, and visibly relaxed. "You see? The situation is not so unmanageable as you feared."
"You're putting on a front," Harry accused.
His father raised an eyebrow. "Perhaps so, but you're going to respect my wishes all the same."
"I... all right, then. If you insist."
"I do."
"But if I research the matter first...?"
"If your research is adequate I will supervise you in the matter. But not while term is underway, Harry. A project like this will require my complete attention."
"A project like what?" asked Draco.
"I want to find a way make his mark stop growing back. Wanded magic. A charmed potion, maybe."
Draco rolled his eyes. "Oh yeah, you and your miracles. Just don't blast his arm completely off, all right? Or blow yourself up during the brewing."