Thorin Oakenshield/Relationships

Bilbo Baggins
Bilbo, over the course of The Hobbit and Pirates of the Caribbean, became Thorin's best friend over just a friend.

In The Hobbit,

Dwalin
Dwalin is Thorin's childhood friend and dwarf best friend (before Bilbo took over this role as Thorin's best friend). The duo were raised together, side by side.

In An Unexpected Journey, it is clear that while Dwalin is loyal and dedicated to Thorin, Dwalin doesn't like his treatment of Bilbo, nor does Dwalin bow down to him, clearly because they are seen as equals. Thorin also can tell what Dwalin is thinking and vice versa.

After the Battle of Five Armies, Thorin dies in his world, but in reality, he himself is revived by  Calypso and sent to the Caribbean to help Bilbo. They meet in Guardians of the Galaxy and both work together to save Bilbo from Ursula and help with the search on land to find Bilbo's and Ariel's daughters, Belle and Melody respectively.