He knew he'd crossed the line that first time when he dropped the boom mic and came to her aid. At the time it wasn't a matter of whether or not it was the right thing to do for his job … a job that had kept him employed for the last 9 years. His brain had made sure to remind him of this fact in the seconds before, as he had stood on the precipice of doing something for her or staying at his post. In the end Brian had come to the conclusion that standing by as Pam cried was not an option. He'd stood by for years as the camera kept rolling while tears fell down her cheeks for this reason or that. His paycheck every other week dictated that he make sure the large microphone in his charge was held over the heads of the workers in this office and that it caught every sound … including Pam's soft sobs.
But, she had looked at him. For the first time, since filming began, she looked directly at him and gave a half-hearted shrug. That one gesture, to Brain, was Pam's non-verbal communication of Help Me and he did. He helped her in that moment, something he had thought of doing many times over the years, but always held back. It hadn't been his place. He was there to simply observe and record. Sure he had exchanged words with the cast of characters inside Dunder Mifflin, but always after the cameras were off. This time he made a call. He'd force the cameras to shut off. He would protect Pam, because it was the right thing to do.
Now he'd crossed another line. He wasn't sure why it had been enough to get himself fired from a job he'd worked tirelessly at all this time, but in the end he knew it was the right choice. He wouldn't stand by and watch as a man took his rage out on the woman he'd grown to care for. They had warned him. Yes, they had told Brian after the first incident that if he got involved with the cast again while the cameras were on that there would be consequences and now they were here. He was fired and forced to leave the company of those he'd been a part of for nearly a decade. Some faces he would miss, other not, but the person that mattered the most was the one that came to apologize for him getting fired.
Always caring … that was Pam. She hadn't fired him and still she felt responsible. He took the moment of her apology to make it clear that he would never hold her responsible. He was there for her always, no matter if he was allowed in the building where she worked at or not. Brian took that moment to remind her that she had his number. He'd given it to her after Roy, but before Jim.
"If you ever need anything … just call and I'll be there for you."
Brian said this as he looked directly into her eyes and he meant it. He never would want to come between Pam and her husband, but it didn't keep him from needing to be there for her. If it were possible for him to keep her safe then he would. He'd made a choice that day of his firing. Pam wouldn't come to any harm as long as he had a say in it.