Short answers, pulled from the story.
Honorius entered the world on the 9th of September 384 within Constantinople as the younger son of Emperor Theodosius I and Aelia Flaccilla. His mother died in 386 leaving him an orphan at two years old before his father remarried Galla.
King Alaric I led Visigoths into Italy during 401 forcing Honorius to move his residence to Ravenna. This coastal city offered protection through marshes and fortifications making it easier to defend than Milan though poorly situated for Central Italy.
The Visigoths poured into Rome after starvation forced defenses open following a siege that began in summer 408. No foreign force had controlled Rome since an invasion eight centuries prior during the Battle of the Allia yet churches remained unharmed.
Zosimus recorded that letters were sent bidding cities to guard themselves after British pleas for help reached the emperor. Modern academics debate whether this rescript applied to Britain or Bruttium in Italy regarding imperial support.
Honorius died of edema on the 15th of August 423 leaving no direct heir behind. Joannes was nominated Emperor during the subsequent interregnum before Theodosius II installed Valentinian III the following year.