This was going to be a difficult conversation to have. But Sherlock was determined to have it. He picked up his mobile and dialled John.
"Sherlock, what's up? I'm on my way home now if that's what you want."
"No, no," Sherlock replied quickly. "It's something a bit more... unpleasant. About the case?"
He heard John breathe in quickly, a sign of stress.
"Don't do anything stupid," he said quietly.
"John," Sherlock began, "I may have to dye-"
"No!" John interrupted fiercely. "You do not have to. You do not need to do anything rash or spur of the moment."
"No," John insisted. "There's Lestrade, and Mycroft, and lots of people who can help. There's no need for you to do anything that is not absolutely necessary."
Sherlock frowned. "John, if it's something that's needed on order to succeed, I don't know what you think the problem is."
"Sherlock," John practically pleaded. "Please. Don't. I don't think I can..." he paused, sniffing.
Growing more emotional, much more, tears, oh god please don't let there be tears.
"John, stop!" Sherlock paused, and John only knew he was still there because of his quiet breaths. "John, I had no clue that you felt so strongly about my hair."
"Your... What?" John stammered.
"My hair," Sherlock repeated. "I don't have to dye it if it's that big of a deal to you. I just thought it would be easier for me to infiltrate the gang if-"
"Wait, what?" John interrupted. "We're talking about your hair?" He sounded extremely skeptical.
"Yes John, my hair. Do try to keep up," Sherlock paused, frowning, and it was evident in his voice when he spoke next. "What did you think we were talking about?"
Sherlock swore he could hear John blushing.
"It's... really not important," he muttered. "Listen, I'm almost home, okay? We can talk about this in a few minutes. Okay? Bye."
Sherlock ended the call on his phone and replaced it in his pocket, clasping his hands under his chin and pacing, pondering what John had meant.
"Oh..."he breathed, finally understanding. "Die. Dye." He nodded to himself.
He attacked John as soon as he came in the door, causing him to drop the carton of milk that he'd remembered to pick up, despite the afternoon shift at the surgery.
"Sherlock?" John asked, sounding rather disbelieving, "are you... hugging me?"
"I've been told that's what this is," Sherlock replied, his arms still around John and his chin resting on John's head. "I realized what the miscommunication meant to you. The thought was displeasing to me."
Sherlock finally released John, who bent down to pick up the milk, which thankfully wasn't leaking. John moved to the kitchen to put it away while Sherlock perched on the couch.
"Not good?" he asked, referring to the hug.
"Oh, no," John said quickly. "Fine. Good even. Just... shocking."
Sherlock smirked. "I am full of surprises."
John chuckled. "I know, believe me, I know."
"Die..." Sherlock muttered to himself. "Die."
He added it to the list of things to fix. (Words mistaken for words that mean bad things. Ex- Die/Dye.)
He also added to the list of things that were acceptable only for John. (Hugs.)