Complex sentence: Arriving in the past, she meets the young Riddle, who calls himself "Satan" and is uncanonically depicted attending Hogwarts at the same time as the Marauders with the time period further uncanonically portrayed as the 1980s.
Split into simpler sentences: Arriving in the past, she meets the young Riddle, who calls himself "Satan". He is uncanonically depicted attending Hogwarts at the same time as the Marauders with the time period further uncanonically portrayed as the 1980s.