In the film The Twilight Saga: New Moon, Bella arrives in Volterra, Italy just in time to save Edward from revealing himself as a vampire to a throng of mortals at the St. Marcus Day festival on March 19th. Attendees of the festival, clad in red, hooded robes, march in procession bearing a statue of St. Marcus to the church in the center of town. In the Twilight world, “St. Marcus” is celebrated by mortals for having rid the town of vampires, when he was, in fact, a vampire himself. Volterra is the home of the Volturri, the lawgivers of the vampire world. Marcus is one of them. Some Twilight fans wear red on March 19th to mark this holiday.
New Moon author Stephanie Meyer borrowed the fictional St. Marcus Day from the real European celebration of St. Mark's Day. She changed the date: St. Mark's Day is April 25th. Because the date coincides with observances of Easter (a moveable feast; the date varies, but it generally occurs in March or April) and a number of other Eurasian spring festivals, it is thought that St. Mark's Day is a Christianized version of a much older, Pagan observance. In the book Ostara, Edain McCoy writes, “As was done with many Pagan festivals in Europe, the early church attempted to refocus the symbolism of Ostara [the spring festival for Germanic Pagans] onto the Feast Day of St. Mark. Instead of being a festival of rebirth, the St. Mark's imagery was concentrated on death and martyrdom, through which Christian rebirth is attained.”
St. Mark is traditionally considered to be the author of the Gospel of Mark in the Christian Bible. He's believed to be the companion of St. Paul, the great early Christian evangelist, that the Book of Acts of the Apostles refers to as “John Mark.” A disciple of Paul, Mark is thought to have used Paul's preaching as the basis for the Gospel. He is also remembered as the founder of the Coptic Church. Coptic tradition holds that Mark appears in the Gospels as the young man who carried water to the house where the Last Supper of Jesus and his Apostles took place, as the young man who ran away naked when Jesus was arrested, and to have poured the water Jesus turned into wine at the wedding at Cana.
Mark is said to have been martyred on April 25th in the year 68 in Alexandria, Egypt. A group of local people resented his trying to turn them away from their traditional gods. They placed a rope around his neck and dragged him through the streets until he was dead. His major shrines are in Egypt and Italy. His Italian shrine is the Basilica de San Marco in Venice, which is traditionally said to be the place where Mark's remains are buried. So, he really does have a connection to Italy, though not specifically to the town of Volterra.
Perhaps because of his martyrdom, many curious traditions grew up over the centuries about the celebration of St. Mark's feast day. In seventeenth through nineteenth century England, especially in the north and the west, folklore held that the wraiths of those who would die the following year made a procession, in the order they would die, through the churchyard and into church at midnight on St. Mark's Eve. Some said the procession would be of coffins, or of headless or rotting corpses. Others said the procession would be of identifiable, ghost-like wraiths, and that one could sit and watch the procession as it went by and thus know who was going to die.
To see these wraiths, folklore claimed, one had to be fasting. Another legend held that one had to be present at the churchyard on St. Mark's Eve for three years in a row, and only in third year would one see the wraiths. Sometimes, these living watchers saw their own wraiths, and died not long after. Another superstition regarding St. Mark's Eve is that on this night, witches who had sold their souls to the devil (or written their names in the devil's book) and wished to keep their unearthly powers had to walk three times around the church backwards, peek through the keyhole, and recite certain words, or their powers would be lost.
Another traditional St. Mark's Eve activity was stirring the ashes of the hearth. If the ashes formed the shape of a shoe, someone who lived in the household would die during the year.
St. Mark's Eve was one of three nights of the year associated with the dead. The others are St. John's Eve and All Hallow's Eve. According to some legends, on these three nights those who have died can return to the earth as spirits. This belief about All Hallow's Eve (Halloween) is a Christian appropriation of the Celtic harvest festival of Samhain, the point when the veil between the living and the dead was at its thinnest, and also the halfway point between autumn and winter. Similarly, St. Mark's Eve marks the halfway point between spring and summer and is associated with the Pagan festival of Ostara. St. John's Eve, traditionally celebrated on June 23rd, is associated with the Pagan feast of Midsummer, or the summer solstice.
Not all of the legends associated with St. Mark's Eve are associated with death, though. The night was also one when young women would try to divine whom their future mates would be. There were a number of ways to accomplish this: by picking twelve leaves of sage at midnight, by walking nine times around a haystack while reciting, “Here's the sheath, now where's the knife?” or by baking a dumb-cake, eating a piece of the cake, then walking backwards to bed without saying a word (hence the word “dumb”). If a woman did any of these things, but especially if she prayed to St. Mark while doing them, she would see the shadow of, or catch a fleeting glimpse of, the man she would someday marry. However, if she went to bed without seeing such a shadow and dreamed of a newly-dug grave, that meant she would die unmarried.
These are largely English customs, though. In Italy, if St. Mark's Day is celebrated at all, it is with feasting, drinking, and/or offering bread to the less fortunate. The custom of wearing red and having a procession seems to be Stephanie Meyer's invention.