I have just finished the chapter where the Sophie seizes a small French cargo ship off the French coast. Since the cargo is all gunpowder, needing very careful handling, Captain Aubrey orders his Lieutenant, James Dillon, to take the ship in to the port of Mahon.
Meanwhile the wife of the French ship's captain has gone into labor with her first child. Dr. Maturin goes over to help deliver the baby. When there are complications he says that he needs to stay on the ship to help with the delivery.
After the baby is born Maturin and Dillon spend their evening eating and drinking some good wine courtesy of the grateful French captain. This is their first chance to honestly discuss their past in the United Irishmen. Neither was involved in the uprising, but they regret how it ended and all the friends they lost. Maturin says he no longer believes in political revolutions.
At one point Dillon asks Maturing if he is really becoming Captain Aubrey's friend. Maturin says that he really appreciates the Captain's good qualities. Dillon says that he can't like the Captain. He is resentful that he didn't get a command. He despises the Captain's eagerness to go after enemy ships to condemn them for profit, partially because he, Dillon, already has money. He also suspects that the Captain may not be truly brave as he let an enemy galley go in a previous engagement, even though he needed to to save a ship in the convoy. Dillon admits that his criticisms may have no basis in fact and are even contradictory. But he says he can't help how he feels. This doesn't mean he won't do his duty though.
In the end he apologizes for having spoken so freely to Maturin. It shows however, that Maturin knows what he is doing as he becomes more involved with the Navy and as he and Aubrey become closer friends.
I also noticed in several scenes how the author describes Maturin's reptilian gaze when he is startled or before he understands the situation.