A/N: This chapter was written in 20 minutes on a tipsy impulse, so I might come back and rewrite it later. Sorry it's so shitty.

John quickly schooled his expression into blank indifference. His student had just had something very personal exposed. This was not something which Sherlock had chosen to confide in him about, but rather had been forced to reveal. It was not his place to interfere, despite the twisting in his stomach and the overwhelming instinct to try to ease his student's obvious pain.

Sherlock followed him as he unlocked the door to the back room, walked in, and grabbed a T-shirt from a drawer. Reminding himself to keep his face neutral, he turned around and handed it to his student, who quickly pulled it over his shivering torso.

Sherlock's heart was racing as he followed his TA into the back prep room and took the offered T-shirt. John hadn't said anything. Was he waiting for an explanation? How was he supposed to talk his way out of this one? John was one of those do-gooder types, and the last thing he wanted was for John to feel some ridiculous obligation to "save" him. Eventually he managed to swallow the lump in his throat and force his voice to work.

"It's not what you think, okay? People know. I don't usually hide them, but Dr. Anderson hates me enough as it is, and I don't want to give him anything he could use against me."

That should work, right? John seemed to share his distaste for the professor, so maybe he'd buy that excuse.

John found himself surprised at the hasty explanation stumbling out of his usually articulate student. It was an explanation that he hadn't expected – based on Sherlock's reluctance for the scars to be seen, he'd assumed that it was a secret. He'd thought that he and Sherlock had shared an unspoken connection, that Sherlock had known that he resented Dr. Anderson, possibly even more than Sherlock did, and wouldn't be gossiping about this.

Still, he knew this wasn't about his own feelings. Sherlock was just another student. So why did he feel that twinge of hurt when he realized that Sherlock had thought that little of him, had thought that he would be gossiping with the prick? That was something to repress and never think about again, he decided. How could he be a competent doctor if even some random undergrad's opinion mattered to him? Better to pretend that his instinct wasn't to envelop Sherlock in a hug and hold him close as if that could make all his pain go away.

Finally, John nodded. "I won't say anything. It's none of my business," he found himself saying, hiding any possible note of hurt in his voice. Had he not been so focused on hiding his own feelings, he might have noticed the same hurt mirrored in Sherlock's eyes when he heard the response.

Even though Sherlock had said that he normally didn't hide his scars, John offered him a clean lab coat anyway, but Sherlock declined. Apparently that wasn't just an attempt to keep him from saying anything then, John thought as he watched Sherlock leave wearing the T-shirt. He had tried to convince Sherlock to go to student health services to get the burn checked out, but even though any costs would be covered by the chemistry department, Sherlock still declined. He had finally allowed Sherlock to leave, though not before giving him the contact information for health services, as well as his personal cell phone number, and instructions to contact health services and himself if the red spot on his chest got worse or didn't seem to be getting better. He tried to push away any thoughts beyond his own professional obligation to his student as he began on the stack of paperwork that was necessary any time a student was injured.

As Sherlock walked away, he told himself that he should have been happy that John had accepted his explanation and not been worried. Once John had found out that Sherlock didn't hide his scars, the bystander effect had fallen into place, a tried and true method to keep anyone from caring too much. It was what he had wanted all along, right? For no one to care. That's what he'd worked so hard to achieve.

So if it stung deep within his chest that John had not even asked if he was okay, well, he told himself that it was just pain from the mild acid burn, nothing more.

A/N Wow. I can't believe I started writing this story so long ago. In an ironic twist, I'm actually now a TA for a chem lab myself. And I've definitely experienced the same frustration with the instructor for my section that John felt with Dr. Anderson.

Funnily enough, though I didn't know it at the time, there really are protocols for what TAs do if a student is hurt (and lots of safety training), and my original guesses were surprisingly accurate. Fortunately I've never been in that situation.

And, just in case anyone was wondering, I wear short sleeves even when I'm teaching. None of my students have commented during the 2 semesters I've been doing this (and trust me when I say that my scars are impossible to miss).