Simplify the following text for a Grade 10 native English-speaking person.
Original: Lucius Aelius Seianus ( 20 BC -- October 18 , AD 31 ) , commonly known as Sejanus , was an ambitious soldier , friend and confidant of the Roman Emperor Tiberius .
Simplified: Sejanus ( Lucius Aelius Seianus 20 BC -- October 18 , AD 31 ) , was an ambitious soldier , friend and confidant of the Roman Emperor Tiberius .