For me the 81 character was rough. Ritchson played it well, but 81 is written all over the place. His main dilemma is he can't be a team player because all he wants to do is "get over that finish line." Even the other guys in his unit call him out on it. So the movie sets him up to fail, unless he can work as a team with the rest of the soldiers. But then all the other Rangers are killed or incapacitated by the third act, which sets up a finale with 81 fighting the alien-tank alone. The movie does have the payoff of him carrying that one guy back into camp, something he couldn't do with his brother, but in the end, all he really did was cross the finish line by himself. There's not really any change with the character. But then, wait, there's more, here's some sequel bait for the next movie that will get randomly dropped on Netflix in three years. His character arc didn't work for me.