[@beyond visions]You're the GM, but generally when I run a game, I make sure to have it open for other characters to intervene... so collaborative but short or open posting.

Rook will probably get his butt kicked by Emmett if he's in a fight. I mean, he's a treasure hunter, not some sort of super-warrior. He wouldn't be a push-over, but he's expecting action from Grace, Emmett, and possibly Othen (but not likely Othen since he knows better than most that without the water we are pretty much dead.)

So, in a fight he is going to...
-Keep his eyes on them and be ready to jump if necessary to avoid initial strikes.
-Disarm himself if posed with weapon combat.
-Not even hold his fists up if confronted hand to hand.

So, in argument he is going to state...
-We have no clue what happened to Emmett's father, only that he has been missing with the entirety of his expedition for a while. (I was thinking something like 10 or even 15 years, but I'm not sure what you had in mind.)
-The Badland Wardes (the guild that Emmett Sr. and Rook were born into... kind of like the Texas Rangers) number in the hundreds, are incapable of liberating the badlands because of the slaver factions that number in the thousands who inhabit the desert. 6 people are not going to succeed where hundreds have failed.
-You have to pick your fights. We can either choose to squabble with slavers, or face the real threat we have yet to even discover.