Some squad-based first-person shooters move so fast that there may be no moments to hear a line from or give a line to an NPC, outside of urgent battle chatter. In games like these, it's hard, if not impossible, to get a sense of the NPCs who fight alongside you.
Therefore, in such games, creating Group Bonding is a much greater challenge. Of course, you can use techniques like Elements of Shared Appearance and Shared Ordeals. Otherwise, though, you may need to slow down the game here and there in order to increase Group Bonding. This might be considered a tradeoff, and no formula will work for every game.
I've seen designers take three different approaches to bringing emotion into squad-based first-person shooters:
It would be foolhardy to try and say that one of these approaches would work for all squad-based first person shooters. However, I'd guess that, if your intuitional radar is on line or your psychic powers have had a recent power-up, you can probably deduce that I favor approaches (2) or (3), depending on the game, or perhaps some mixture of the two.