I love Ellen so much that I too have a similiar mental block, but if you dig down, I think that Ellen would be a delicious bad guy/gal. Samantha Ferris plays Ellen with a lot of character (pardon the phrasing) -- the freeness of the villian role would rock.

(Plus, we really only have her word that she was a friend of John's -- John's dead and can't refute, and we know John never talked to the boys about the Roadhouse. Hrm, a lovely idea)