Complex sentence: Publius Cornelius Lentulus Scipio (II), was most probably Poppaea's step brother, he was a consul in 56 and later served as a senator.
Split into simpler sentences: Publius Cornelius Lentulus Scipio (II), was most probably Poppaea's step brother. Luntulus Scipio II served as consul in 56 and later served as a senator.