He half listened to the little backstory David offered up, eyes still watching for any indication of the swimmer resurfacing. He couldn't help but think that it was strange that it could have tried to attack David when he was standing out on the pier; it probably had the opportunity, not that Brennan was hoping that it would attack the other man. It just didn't fit the bill, and Brennan just sort of hoped that the creature might have been on it's last leg, damaged before making it's way over here. He didn't want to imagine the possibility of it having enough brain power to lure more this way because, while he was a pretty good fighter, he wouldn't know what to do with David, since he really couldn't predict how he would react. Briefly, Brennan ran through a list of scenarios, trying to plan for anything. He was stalled a bit when the "what if he passes out" idea came up? He was strong, but he wasn't strong enough nor fast enough to carry David back somewhere safe, nor could he let the infected get close to the safehouse.
Needless to say, David not passing out in the event of an attack was at the top of his list of prayers.
"Hopefully there really is only the one." He answered, looking David in the eye briefly before, yet again, checking the pier. "How did it look? Did it look fully functional?" He then asked, sort of hoping David would say it was missing it's legs or something.