In The Tempest, Stephano and Trinculo appear to be kinder and more respectful to Caliban than Prospero is to Caliban and this is one of the reasons why Caliban decides to follow their rule instead of continuing to follow Prospero. However, Stephano and Trinculo still see Caliban as a base creature, and they only use him to try to gain power on the island. Caliban says that he will show the two the secrets of magic on the island, and Stephano and Trinculo think that this will be key in usurping Prospero and taking Miranda for themselves. So although they do not speak cruelly to Caliban in the way that Prospero does, they still do not truly respect Caliban in the play.
Caliban perceiving that Stephano and Trinculo are not so firm and vigilant as Prospero is,he perhaps thinks that if they become his master,it would be easier for him to follow his own interests. It also shows that Caliban is taking up the civilised man's 'tool'/'mechanism' for manipulating others.