Archer's True Name is Paris (パリス?), the brother of Hector. The sheep that follows him is in fact, the Greek god Apollo. Paris is the younger brother of the Hero of Troy and member of the Nine Worthies Hector, who stole Helen away from King Menelaus (though it was promised by a goddess), causing the Trojan War. Struggling with Hector, even after his brother died, Paris played an active part in defeating Achilles. Born the son of the King and Queen of Troy, Priam and Hecuba, Paris was abandoned atop Mount Eday, according to a prophecy that "a child born this day would lead Troy to ruin."
But the baby survived on bear's milk, until he was found by Agelaus, (the very man who abandoned Paris by the king's command) who decided to raise him along with his own children. In addition, it is the meaning of the bag that should have been Paris, and it is said that he was put in the bag that he was put in when he was taken home from the mountain.
Paris grew up as a beautiful boy who had nothing to do, until one day Athena, Aphrodite, and Hera, the three most beautiful goddesses, chose him to act as a judge.
Hera offered a throne and wealth, Athena granted victory and wisdom, and Aphrodite promised the most beautiful woman in Greece, Helen of Sparta. In turn, Paris chose Aphrodite. But, Helen was already a wife of Menelaus, so, inevitably, Paris made away with Helen. So the men who once fought to be Helen's husband, after Helen was taken, chose to collaborate to get her back, swearing a pledge to do so. The earliest battle was inevitable,and Troy fell into war with the Greek Allies. It was the beginning of the Trojan War, which it was referred to as later.
Although it is not the height of his physical prowess, Apollo has arbitrarily declared "Paris-chan was the most shining at this time!"and changed him into this state.