Heathcliff is a man with a terribly short fuse who will not kneel before anyone till his last breath. Growing up Backstreets-borne in the Wuthering Heights, where he was heavily mistreated, he is experienced in such hostile environments with the barbed character to match. 

In the Wuthering Heights, it was his love for Catherine which kept him going. Catherine is now forgotten to the world (dead), everyone but him.

He has a very distinct British Cockney accent, often using slang in his speech.