To be friends with Tod (in the first film)
To help his master, Amos Slade kill Tod (temporarily;formerly)
To join the Singing Strays (in the midquel)
Sleeps in his dog house and never forgets about his best friend, Tod
Copper is one of the titular protagonists of The Fox and the Hound and it's 2006 midquel, alongside Tod. He is Tod's best friend (despite the fact that Tod and Copper should be natural enemies), Amos Slade's youngest pet dog and the adoptive son of Amos Slade's oldest dog, Chief.
Despite being a protagonist, Copper became an antagonist when he became an adult since he was willing to help Amos Slade with his plans to try and kill his own best friend, Tod, but he reforms in the end as he became friends with Tod again while protecting him from his master, Amos from trying to kill him.