Mentis had been keeping to himself the whole time, poking his index fingers together, with his head lowered, and his eyes shyly cast up at the group. While the others got antiquated with each other, or otherwise gave annoyed glares. This is why he chose to stay out of conversation, unless of course someone approached him, there was less chance of annoying others that way.
He didn't really know how he could contribute anyway, he had no muscles to flex, weapons to parade about or abilities to show off. No unless someone got hurt, he was pretty much useless, unless one of them wanted someone they could talk to. He had always been a good listener, or so he has been told.

Because of his observing the others, Mentis knew immediately when someone was wrong he could see them tense as they seemed to either sense something, or notice something off in the distant. Mentis found himself growing nervous again, in reaction to others, and glanced over to Arya as she gave the order for everyone to get into the ship. Mentis would have managed to get there on his own, though it might have taken him a while, as he would have politely stood aside and let everyone else on first, it was only good manners despite the situation. This didn't come to be however, as the boy felt himself being grabbed by another.

"Uh?..oh, ok"
His voice was barely audible as he fell into a sort of ragdoll state, letting himself be dragged and ushered towards the ship, with no resistance to the one grabbing him. As they got to the ship, Mentis quickly stumbled through the door, and off to the side to get out of everyone's way, though he stopped and turned to face Tristan, smiling to the larger man with much gratitude.

"Thank you, Tristan" 
he spoke quietly, probably wouldn't even be heard over all the noise and chaos. The boy then turned his attention to the others, watching again quietly, as they all managed to get themselves onto the ship one way or another. He was relieved for a time, though knew that until they all settled down, they were still in danger.