Who unites with the dwarves?

In J.R.R. Tolkien's "The Hobbit," the character who unites with the dwarves is Bilbo Baggins, the titular hobbit. He joins the company led by Thorin Oakenshield on their quest to reclaim the Lonely Mountain and its treasure from the dragon Smaug. Bilbo's cleverness and bravery play a crucial role in the success of their journey, as he helps the dwarves navigate various challenges along the way. Throughout the adventure, he grows from a reluctant participant to a key member of the group.