Sherlock did join John's Medical course, though (and much to the first year's chagrin) he was quite splendidly horrible at it.

Day after day Sherlock would be left standing in front of a smoking, hissing cauldron with soot on his face and those adorable curls yanked beyond repair.

Not that the rest of the class faired any better, mind you. Medical Potions were not merely about memorizing a list of materials and mixing correctly. Each potion would be tailored to a specific person, or rather, a specific person type. Young boys reacted differently than older boys would, and old women were drastically different than old men, for example. Then there were potions that had to be crafted to effect gender, and not only sex, of the patient. For instance, an antidepressant potion for cisgendered boys would have unpredictable effects on a girl of the same age regardless of their chromosomal make up. Each potion had a basic form to be mastered, but it took a keen eye and empathic hand to make it just right for the situation.

Sherlock had the keen eye, that's for sure. And a powerful mind. He swiftly moved through the practical stages of each potion, memorizing the recipes and the minutiae for each deviation. But he could never produce more than the basic draught with success.

Even when the class was tasked with making a blemish clearing potion for themselves, something John assured them would come in handy for more than just banquet nights (have you ever come down with beezlebug boils? Thought not.) Sherlock wound up clearing his skin of all oils-rendering his face parched and lips cracking. While the class giggled, John came swiftly to his rescue with a rehydrating charm, though not before dropping a Mummy pun himself.

The rest of the class also failed to produce a perfect draught, but at least no one else had desiccated themselves.

"Okay, Class. Do NOT beat yourselves up about this. Medical Potions are TRICKEY. Trickier than even Defense Against the Dark Arts spells. These potions require you to intimately know your patient, their emotions and their hurts. You need to have an understanding for not only the body, but also the soul of each person," John looked around. Quite a few of his students were scowling into cauldrons to hide tears of frustration. He smiled gently, "I am not marking you on whether you can make the perfect pancreatic poultice for an octogenarian occlomancer. I will be marking you on effort, the basic recipes, and… oh yeah, EFFORT. Now get out of here,"

The class chuckled, all but Sherlock looking visibly reassured. It was an odd bunch. Mostly Hufflepuffs of course, but there were more Gryffindors and Slytherins than John would have expected. Ravenclaws filled up the rest of the seating chart, but that was also to be expected.

The class filed out, grousing amongst themselves, while John settled back at the desk with his planner. He had a free hour before Quidditch practice, and he wanted to get some grading done first.

It was very cool, he mused, being an assistant professor to Slughorn, but this was truly fun. He enjoyed the looks of determined frustration on his student's faces, and he delighted with them when one of them got a potion right. He knew it wouldn't be until at least the midterm exams before one of them created a perfect potion, but there was tremendous progress in everyone even in these first few weeks.

Everyone except…

"Sherlock?" John jumped when Sherlock thumped his textbook down on his desk, standing stiffly before him with his head down and shoulders hunched.

"Sher, look, no, it's alright. I meant it. You're grades aren't suffering, and your potions are-," Sherlock cut him off.

"Getting worse, if anything," Sherlock looked up through his unruly bangs at John, "I… I don't know what I'm doing wrong," it sounded like the admission hurt,

"I know the recipes, I KNOW how to alter them. But WHY. CAN'T. I. MAKE. THEM?"

John studied the younger boy thoughtfully. It would be one thing if he was just having trouble with making potions for other demographics. But Sherlock couldn't produce a safe potion for himself… And that worried John. As a professor, and certainly as a friend.

"Sherlock… Please understand. You're brilliant," He smirked sadly at the look on Sherlock's face, "But… Listen. When you do your deductions of people, yeah? How do you do that?"

That startled Sherlock. It clearly wasn't the question he'd expected.

"Um. Well. They're really just observations of the truly obvious things that people don't pay attention to about themselves and others," Sherlock shrugged, "I've never really thought about HOW I do them… I just… I just see the facts,"

John nodded, "That's how I look at patients. During… During the Battle… I created a few spells out of panic. I looked at my classmates dying around me, being injured around me, and I… just SAW how they had been injured, and I SAW how they needed help," He paused, "My friend Greg. He had his shoulder nearly completely crushed by some falling rock. I just… I could see the trauma of the bone, of the flesh and muscles. I knew, by instinct, what to do. I don't remember those spells now, of course. I don't even know if they were proper spells. I could feel my magic, and I made it into the tool I needed. Then later, after the battle, when I helping in the hospital wing, I could see the differences between the patients. I could tell the difference between the pain of an old man who had suffered it for his whole life apart from the pain of a young girl who'd been hurt by someone she'd trusted. It tastes different, smells different. And you need to be able to know that difference,"

Sherlock looked somber, listening to John talk of the Battle and its aftermath. But he still didn't look convinced, "You're… you're saying that while I can see it all… I don't know it. I don't know… people,"

John hated the tiny, scared tone of his friend's voice but, "Yes. You know humanity, but you don't know individual people. Until you begin to make more friends, Sherlock, or even just get to know others, you will probably have a lot of trouble with the actual potions. However, like I said. You're certainly not going to get bad marks in this course for not being perfect,"

"John… may, may I try one more potion?" John blinked, then shrugged,

"Sure, Sher. What do you want to try?"

They settled on a quick and simple headache draught. Dried Willow Bark Pixies, kraken saliva, and a few other ingredients. Sherlock started to mix, creating the basic potion. After a few minutes, it bubbled peacefully away, a light shade of blue.

"Very good Sher. Now, for younger boys, you want to add more miffle berries," John started, but Sherlock was shaking his head. Instead, Sherlock grabbed another two dried pixies, and a clump of seaweed and added them to the cauldron.

"Who are you…" John started to ask, but when the potion turned a phosphorescent lavender, he broke out grinning, "Sherlock! That's perfect!"

Smelling slightly of cut grass, a blinding lavender, and with bubbles no larger than a galleon in diameter, Sherlock had almost effortlessly created a headache relief potion for a teenage boy.

"You're… you're the only friend I have… so if I know anyone, it's you, John," Sherlock bit his lip, embarrassed, "I figured… I might be able to do it,"

John grabbed his friend in a tight hug, laughing, "That's great Sher. And I'll certainly be needing some of this after practice,"

John helped Sherlock bottle the potion, placing a few vials into Sherlock's pack, pocketing one himself, and then placing the rest in the box that each afternoon would be delivered to the Infirmary.

As they left the classroom, Sherlock turning to go to his next class, and John toward the Quidditch pitch, John called over his shoulder, "I guess we'll have to start getting you some friends!"

John laughed at Sherlock's overly dramatic shudder, then hurried off to practice.

Sherlock, still trying to conceal his pleased smile, wandered slowly to his herbology course. Make more friends? More than just John?

It might… it might be a worthwhile experiment.