Prospero
"If thou neglect'st or dost unwillingly What I command, I'll rack thee with old cramps, Fill all thy bones with aches, make thee
roar That beasts shall tremble at thy din."
Caliban
"I must obey His art is of such power It would control my dam's god, Setebos, and make a vassal of him."
Prospero
"So slave, hence."
(I.ii. 243-251)
The Prospero and Caliban relationship is based off of subjugation which is expressed through threat as he uses phrases such as "I'll rack thee with old cramps."
Caliban is a native of the island, and offspring to a powerful witch, which means that he has a claim to the island.
Prospero has taught Caliban how to speak. He uses controlling expressions towards him. Caliban can only reply with a similar language cause the only tone that he has seen in language is power and control by Prospero.