Brennan had always known there was going to be a time when he was going to simply lose it, and he also knew that it would be terrible. Thankfully, this wasn't that moment, but his talkativeness seemed to be there to remind him that it is certainly going to happen, and after four years of festering, it almost appeared keen to happen soon. He had a small fear that his breakdown wouldn't be emotional; he had never been an emotional person in his life and he didn't think that the end of the world was really going to change that. No, he knew that if he were to unravel at the seams, it would be in the middle of the defense for his own life, and he would just lose control of himself. It sounded dark because it was; he wasn't a pessimist, but he was honest with himself. Something similar had happened when he was younger, in his early twenties, and he had literally just shut down. It was actually terrifying, because he couldn't move, and he had no idea what was happening to him. The doctors had said something about a build-up of stress hormones, which, over time, have extremely adverse affects on the body. He had lost a lot of weight and had gotten some sort of opportunistic infection, and they thought it was a wonder he hadn't dropped dead just from the levels of stress hormone.
They had warned him to keep his stress level low after that, and he had certainly tried to do so before the Outbreak. He'd actually gotten rather good at keeping himself healthy, mostly out of worry of having the same thing happen again. Knowing that you were at risk for something was a good enough motivator to keep his body running right. After the Outbreak, he never got the chance. And when he put his life behind his duty, he further compromised himself. When he told Lucretia about the Immune that run themselves into the ground, he included himself with them. It didn't even matter that he was conscious of the fact. It was a part of him, he was stubborn, and his responsibility was all he really had left.
"I've met quite a few people who don't take this seriously." He resisted the urge to look back at the safehouse. He knew that some of the reason for people's lack of seriousness was a defense mechanism, but it didn't make him any less annoyed when people wasted time better spent taking care of more important things. "You'd be surprised how some of them slip through." Brennan almost wanted to laugh at her comment; no one wants to run themselves into the ground. Many of them no exactly what they're doing, know exactly what's going to happen to them, they just can't help themselves. "It just happens. I don't want to see the day when it happens, but I know it will," he wondered if that sounded personal. It probably did, "It's strange to think about it, when no one's ever going to know why you did it."
The pair of swimmers had hardly been a threat, not even enough to really get his heart-rate to increase. It was probably due to all the cortisol in his body; he was sure his blood pressure was already elevated under normal circumstances. He actually measured his heart rate by how it goes down which is horribly unhealthy, though probably why he sleeps so well.
"I could have been worse," he offered. "Just two, with one not even fully out of the water, is one of the better days."