Simplify the following text for a Grade 9 native English-speaking person.
Original: At the outset of his reign , Commodus , aged 19 , inherited many of his father 's senior advisers , notably Tiberius Claudius Pompeianus ( the second husband of Commodus 's sister Lucilla ) , his father-in-law Gaius Bruttius Praesens , Titus Fundanius Vitrasius Pollio , and Aufidius Victorinus , who was Prefect of the City of Rome .
Simplified: At the outset of his reign , Commodus , aged 19 , inherited many of his father 's senior advisers .