Arcadius (Ἀρκάδιος ; 377 – 1 May 408) was Roman emperor from 383 to his death in 408. He was the eldest son of the Augustus Theodosius I (379-395) and his first wife Aelia Flaccilla, and the brother of Honorius (393-423). Arcadius ruled the eastern half of the empire from 395, when their father died, while Honorius ruled the west. A weak ruler, his reign was dominated by a series of powerful ministers and by his wife, Aelia Eudoxia.
Arcadius was born in 377 in Hispania, the eldest son of Theodosius I and Aelia Flaccilla, and brother of Honorius. On 16 January 383, his father declared the five-year-old Arcadius an Augustus and co-ruler for the eastern half of the Empire. Ten years later a corresponding declaration made Honorius Augustus of the western half. Arcadius passed his early years under the tutelage of the rhetorician Themistius and Arsenius Zonaras, a monk.
Both of Theodosius' sons were young and inexperienced, susceptible to being dominated by ambitious subordinates. In 394 Arcadius briefly exercised independent power with the help of his advisors in Constantinople, when his father Theodosius went west to fight Arbogastes and Eugenius. Theodosius died on 17 January 395, and Arcadius, still aged only 17, fell under the influence of the praetorian prefect of the East, Rufinus. Honorius, aged 10, was consigned to the guardianship of the magister militum Stilicho. Rufinus ambitiously sought to marry his daughter to Arcadius and thereby gain the prestige of being the emperor's father-in-law. However, when the prefect was called away to business in Antioch (where according to Zosimus, Rufinus had Lucianus, the comes orientis, flogged to death with whips loaded with lead), Arcadius was shown a painting of Aelia Eudoxia, the daughter of the deceased Frankish magister militum per orientem, Bauto. Seeing the young emperor's interest in Eudoxia, Eutropius, the eunuch praepositus sacri cubiculi, arranged for the two to meet. Arcadius fell in love and a marriage was quickly arranged, with the ceremony performed on 27 April 395.