I think Willoughby is a predator because he victimizes girls for his gain and I do not believe it is a coincidence the girls all have similarities that make them an easier target and/or easier for him to manipulate. He is a predator with a preference for a particular kind of victim.

Is designating certain kind of girls and women fair game a general rule accepted by a majority of society or one that is a twisted code of honor among cads? Is there a reference? My impression is that Willoughby’s seduction of Eliza is not more acceptable to people of good character because her mother was a fallen woman. Both Col Brandon and Elinor are disgusted with his behavior and there is no hint they believe she was in anyway fair game because of her history.

I don't think Eliza was signaling to all the cads in Bath that she was willing to be seduced. You said Eliza did not behave with the special discretion a girl with her background ought in order to be considered respectable by society. My question is how do you know people in Bath knew her history and expected her to act with special discretion? Even the angelic but extremely inquisitive Mrs. Jennings does not know the real story. She believes Eliza is the natural daughter of Col Brandon.

It is not improper for Eliza and Friend to go places in Bath without a chaperone—in NA Catherine Morland and Isabella Thorpe (a confirmed flirt) do just that without censure. I think Col Brandon is noting the father of Eliza’s friend for negligence when he says “for he had been generally confined to the house, while the girls were ranging over the town and making what acquaintance they chose” (Ch. 31). He expected Friend’s Father to monitor Eliza’s new acquaintance like Mr. Allen did for Catherin in NA, Ch. 3.