This is one of those happy feasts that's celebrated on the same day in both the Eastern and Western calendars. Hooray for Agatha.
She's apparently one of the top few virgin martyrs celebrated in the west; the basic plotline is familiar. A girl of exceptional beauty, she was sought by a Roman governor named Quintian. She explained her vow of chastity, and in exchange he explained his understanding of Roman justice.
First, he tried to blackmail her by promising not to charge her with Christianity. Failure to communicate: he didn't understand that Christianity was not a crime to the Christians, and that in the third century, suffering and martyrdom were like beer and pizza (something devoutly to be wished).
Second, he committed her to a brothel, hoping to cure her persistent and pernicious virginity. At this point, I begin to question Quintian's intelligence. If she wasn't willing to sleep with a wealthy patrician who probably took regular baths, why would she sleep with the sort of men who need to pay women to have sex with them? You may well answer fear, to which I refer you to his first attempt.
Here's the part of the story that never failed to captivate the readers: the tortures. I must believe that polytheists and Christians alike enjoyed these stories because they are always recounted in such detail. The Greek Orthodox Online Chapel tells us that she was subjected "many harsh torments" but SQPN.com tells us that she was "beaten, imprisoned, tortured, [and] her breasts were crushed and cut off. In that version, which identifies her persecutor as Quinctianus, she says, “Cruel man, have you forgotten your mother and the breast that nourished you, that you dare to mutilate me this way?” Whether she was healed by St. Peter (as one version claims) or not, she was re-imprisoned and then rolled on hot coals. An earthquake interrupted all this, killing a friend of QuinctiANUS and causing him to flee for his life. Then she settled back, thanked God for the relief of her pains, and died.
There were a few post-mortem miracles worth reporting. An angel placed a headstone on her grave. When Mount Etna was erupting, the faithful carried her veil in a procession, saving Catania. When the Turks were massing to invade Malta, she intervened again to save it.