He's...not really sure if he should let on how much he knows.
Prompto figures it can't be much of a secret that he knows. He's mentioned that he lurks in that group chat, even if he and the other guys are often too occupied to say much in it. And if nothing else...well...he's noticed that Taro seems anxious lately.
He can hardly blame the guy. Running off to the Lucian wilds from who knows how far, adopting the faces of complete strangers just to escape the eyes of the organization that experimented on them...underneath all the jokes, they've got to be scared.
In many ways, it's a familiar feeling to Prompto.
He's not really sure whether to just...drop into the group chat to give everyone his well wishes without any prior warning, or maybe talk to Taro first. Or even whether to say anything in the group chat at all, given that someone with Umbrella's coordinates is apparently in there. He may need to talk this over with the guys, maybe look into the security on their phones and double check that everything is as private as it can be. He can't imagine a Crownsguard make would have many vulnerabilities, but these days, one can't be too sure...
Without really meaning to, Prompto catches Taro's glance from his place standing by the Regalia, loading it up for their next stop. He may not know exactly what's going on in Taro's head, down to the letter...but he can at least lighten the mood. It's what he does best.
Prompto grins, waving for Taro to come to the car. The group has a bit of a drive ahead of them.
Better that they stay close....and that the guys sit this one out, too.