Downton Abbey star Siobhan Finneran says she gets a kick out of playing the most-hated character on the ITV1 period drama.
The actress, 46, stars alongside Hugh Bonneville and Jessica Brown Findlay as bitter spinster Sarah O'Brien, Lady Grantham's scheming lady's maid.
She told the Radio Times: "I actually have great fun being sniffy to everyone! I love O'Brien the most when she's spiteful and has a brilliant put-down. She's a clever lady and a bad enemy to make."
She added: "Some people like to think she was just born bad, but I believe that at some point she has had some damage done to her.
"I have invented a back story for her, although whether that matches what (creator) Julian (Fellowes) had in mind, I'm not sure.
"The fact that she had a nephew and family she cared about came as a bit of a surprise."
The Benidorm actress said she would like to see her alter ego find romance.
"O'Brien with a boyfriend would be stupendous! Who would be brave enough to take her on a date?
"Kevin Doyle, who plays Molesley, and I are always speculating what our characters would be like on a date - it would be hilarious," she told the magazine.