Adam breathed evenly. His feet pounding against the ground beneath him provided a good rhythm. It was repetitive. It was calming. Running had always soothed him when he got like this. It had been a while since the desire had risen so strongly though. Standing up to Mac had been exciting and terrifying, and the whole time all Adam had really wanted was to surrender to those stormy eyes. He'd only fought so hard because he knew he was right. They weren't prepared and the thought of what they'd need to do –the part of himself Adam would have to share- in order to be ready scared the hell out of him. Adam stopped mid-stride; all his energy suddenly evaporated. He couldn't do this. He couldn't share this part of his life with Mac. Not knowing the way he felt about the older man. Closing his eyes, Adam forced himself to keep breathing. When the panic attack that had been building passed, Adam turned around and headed back to Mac's apartment. Filled with a new determination, Adam began walking with a purpose. He was in control of this. It wasn't like before. Mac would never hurt him and this time Adam was the one with all the knowledge. He could do this.

Mac looked up at the sound of the door. Without a word Adam went straight towards the bedrooms, leaving Mac to look on with trepidation. He returned a moment later with something clenched in his right hand. Mac stood up from his position on the sofa and regarded Adam carefully. With one last deep breath, Adam raised his hand and showed Mac the collar he'd worn the previous night.

"Adam?" Mac spoke eventually; having no idea what was going on.

"Take it," Adam spoke quickly and quietly; eyes not meeting Mac's. "If we're doing this right, only you get to decide when and where I wear this. I can ask for it, but you have to put it on me." Mac took the collar tentatively. He had the feeling he didn't understand the implications here, but he was just happy Adam seemed to be on board. "There's more," Adam moved on quickly, still avoiding Mac's gaze. "There are things you need to know. About me. About… this."

"Adam, look at me." Mac was using that tone again – calming but with distinct authority running through. It made Adam obey without thinking; looking Mac in the eye. "It's ok," Mac continued. "You can tell me. I'm listening."

"Can we sit?" Adam's voice was timid, but Mac smiled reassuringly and they moved to the sofa.

"Take your time," Mac encouraged Adam, who seemed close to losing it. "There's no rush."

"I'm not ready for this," Adam admitted. "I've been trying so hard to hide this part of myself."

"It's ok," Mac replied and a quick glance showed Adam the supportive look on Mac's face. "Just start slow. How long ago did this start for you?"

"It's been in me almost my whole life," Adam sighed. "I only knew what to call it when I was about 16; didn't do anything about it until I moved to New York."

"Your ex?" Mac prompted. Adam nodded slowly.

"He was my first. He used that against me. Until I started going to the club with him, I'd never even heard words like 'limits' or 'safe word.' Rick was the one to tell me about that stuff. Before him, I just assumed it was my fault…" Adam's expression became sad, and Mac touched his knee in reaction.

"What, Adam? What was your fault?"

"That I didn't like some of the stuff we did. I figured it was all or nothing. Nobody ever told me I didn't have to enjoy it all, and he always made me feel bad when I didn't." Adam's chin was on his chest by now. Mac squeezed his knee a little.

"What made you break it off?"

"The man we met at the club," Adam looked back up to Mac's face slowly. "He wanted to share me. I didn't understand how someone could love me and still want to give me to someone else. It was the biggest fight we ever had. He accused me of not respecting him; told me I was a bad sub and that nobody would want me if I left him."

"But you left anyway?"

"Thanks to you." Mac looked shocked at this, and Adam laughed softly. "I'd applied to work at the lab behind his back. I got the letter telling me you wanted to interview me the morning before. The idea that someone else thought I was worth something, even if it was only for work, it helped. So I left, with nothing but the clothes I was wearing. I bought myself a new outfit for the interview and, by some miracle, you hired me. I never looked back after that." Mac swallowed thickly at the contentment he saw in Adam's eyes. He almost didn't want to ask the question on his lips.

"Don't you miss it?" Adam laughed again.

"All the time. I know more now, so I know what I really need. That makes it harder sometimes, but I won't put myself in that position again."

"What do you need?" Mac asked softly, and Adam turned his gaze away before answering.

"Someone to belong to," He replied quietly. "At work there are so many people demanding my time and that part of me can't help but slip through. I was never looking for a 24/7 thing; just someone who would see when I was falling and make sure it was them I fell for." Mac felt his heart stutter at Adam's softly spoken words.

"Do you know what BDSM stands for?" Adam asked suddenly. Mac forced himself to release Adam's knee at the question; not wanting to squeeze too tight and hurt the younger man.

"It's a combination," Mac eventually spoke. "Of three different terms. Bondage and Discipline, Dominance and Submission, and Sadism and Masochism." Adam nodded; he should have expected Mac to have done his homework.

"I don't like pain," Adam tried to explain. "Not really. A little edge is always good, but the idea of being beaten…" Adam shook off the shudder of old memories and continued. "Dominance and submission is my main thing. I do like bondage, but nothing heavy." Adam seemed lost now; not sure how to explain his needs to Mac. He was talking about his deepest secret to his freakin' boss! He's a little more than your boss. A small voice in his head pointed out.

"It's emotional for you," Mac supplied and Adam nodded. Mac suddenly felt bad for pushing this issue. He knew they needed to catch these killers, and the way he felt when Adam was curled into his lap was definitely a factor, but he'd pushed too hard. Adam was giving up a lot here. Mac should have realised how hard it was for him.

"Thank you," Mac spoke softly, earning a confused look from Adam. "For sharing this with me." Adam blushed a little but nodded. "You know you can trust me, right?"

"Of course," Adam answered quickly.

"It's been a trying morning," Mac said, changing the mood with a smile. "What do you say I take you out for breakfast?" Adam nodded.

"Let me just put some fresh clothes on." Mac nodded and watched Adam leave, hand tightening on the collar he belatedly realised he was still holding.