Why does Douglass seek his master's protection against Mr. Covey's brutality? What is the result of his request?

Douglass is left bleeding and weak, but he determines to go to Auld to complain about Covey's treatment.  Although Auld momentarily seems sympathetic to Douglass, he soon tells Douglass he must go back to Covey's farm and continue to work for him.

That's because Covey is literally beating Douglas to death. Unfortunatly Douglas's  old master sides with Covey. He tells Douglass that Covey is  a good slave manager and that Douglas deserved to get beaten. He lets Douglas stay the night but is sent back in the morning.