[4][3] Eucherius was the only son of Stilicho and Serana, but he had two sisters, Maria and Thermantia,[3] both of whom married Emperor Honorius, from February 398–407/408 and 408–August 408, respectively.

[3] Stilicho served as a general for Eastern Emperor Theodosius and proved himself capable at the Battle of the Frigidus in 394, where Theodosius defeated Eugenius and gained control of both the Eastern Roman Empire and the Western Roman Empire, becoming the last emperor to control both.

The exact reasoning for this is disputed: the historian Peter Heather suggests that Stilicho intended to use Illyricum to base Visigothic King Alaric I, in order to use his troops against the Alans, Vandals and Sueves that were threatening to raid the west;[12] Bury suggests that the actual goal of this plan was to establish a separate domain to be ruled by Eucherius, splitting the Roman Empire into three and making Eucherius a third emperor.

[3] This office made him a vir clarissimus (literally "very famous man", a formal indication of an individual's rank).

However, the historian Edward Gibbon viewed it instead as being proof against the veracity of the allegations, as Stilicho would be unlikely to keep Eucherius in such a low office for so long if he intended him to one day become emperor.

[17] While this was happening, Alaric demanded payment for the time he had spent in Epirus waiting to attack Illyricum, and marched to the Julian Alps, threatening to invade Italy if he was not given large amounts of money.

The Roman Senate initially favored declaring war against Alaric, until Stilicho influenced them to give in to his demands.

Bury views this as an attempt by Stilicho to seize control of Illyricum, if not the entirety of the Eastern Empire, for Eucherius, without indebting himself further to Alaric by using his forces.

[23] Eucherius fled to Rome, aided by some of the soldiers of his father, and he was able to find refuge in a church for some time but was murdered by Arsacius and Terentius on Honorius' orders.