Great answers on Query Letters from Olivia and Sharon! Thanks, ladies.

Regarding the protagonist background story, let's take a couple famous examples and consider possible background stories:

In Harry Potter, Harry is the protagonist. Background stories might include his recollection of the night he gained his scar or an early memory of being bullied by Dudley, before he had the power to do anything about it.

In Twilight, we might read Bella's recollection of her parents' divorce.

In Lord of the Rings, we might read about the time Frodo first met Gandalf.

Whatever you write, you want your protagonist to be likable and relatable. Make us LOVE your character - because he's witty and charming, because we empathize, because we're indignant at the way he's treated, or through whatever emotional connection you can create for us.

Regards,
Michelle