[Teresa Edgerton]

If you make readers feel sorry for a character at the beginning, it usually takes a series of genuinely heinous acts before they begin to withhold that sympathy.

The Gormenghast books by Mervyn Peake provide a very good example. When you first meet Steerpike (who falls somewhere between anti-hero and villain) he is so utterly downtrodden, sympathy is established early, and takes a long time to erode. In fact, for some readers it holds until the end.

Another example is Thackeray's Barry Lyndon. The main character has such miserable luck at the beginning, it's only when he's in more prosperous circumstances that his actions begin to appear mean and despicable.