Squall is pretty much always serious, so really, it shouldn't be any sort of surprise that the situation itself is similarly serious. True, he trusts people, but it's never been easy for him to. It's always taken work for him to realize that he does maybe trust people whether that comes from realizing the depths of his feeling for one single person or from what had come of the Thirteenth Cycle.

(He still has the crystal, he's pretty sure. He's just not sure if it'll come hand if he asks it. No one else has demonstrated an ability for anything even remotely similar, on board the satellite and Squall has no reason to assume that he'll be the exception to the rule.)

It takes a moment before he answers. He's never really thought of friendship as being trust. Yes, he's realized that he trusts certain people to have his back when he needs them to, but he has a sneaking suspicion that isn't quite the same as what Selphie has in mind. It's... more of a professional thing, to him. A trust that someone can do their job well enough to not need his concern, and he's not really sure that he can actually successfully articulate that fact.

"I do trust people."