Why did Brown compare himself with a man "prone to domestic violence, kidnapping, possibly murder and digging up his dead lover"?

During 'Business' Questions yesterday Theresa May asked Leader of the House Harriet Harman about Gordon Brown's magazine interview in which he likened himself to Heathcliff.

Theresa May MP: "Yesterday, the Prime Minister likened himself to Heathcliff. I imagine that most people would be disturbed by this comparison—as indeed it seems was Andrew McCarthy of the Brontë parsonage museum in Yorkshire, who explained that:

“Heathcliff is a man prone to domestic violence, kidnapping, possibly murder and digging up his dead lover. He is moody, and unkind to animals.”

Can the Prime Minister make a statement explaining which of those characteristics is most like him?"

Ms Harman did not respond.