With Thorin and the dwarves in prison, Bilbo becomes responsible for the fate of the entire group. He uses the power of the ring to stay invisible and learn what he must to secure their escape. His resourcefulness grows, and he develops an escape plan that proves to be successful. He also exercises bravery in stealing the keys from the prison guard. He undertakes a risk in persuading the dwarves to go along with his plan, and that proves to be a risk worth taking.
You also see further characterization of the dwarves in this chapter when, under the leadership of Thorin, they refuse to reveal the nature of their journey to the Elvenking. This is part bravery and part dwarvish greed — refusal to share.
