Loyalty Above All (джен)

Barty Crouch Jr. was not always a ruthless torturer on the verge of insanity. He was an average Hogwarts student once, with a distant father and an unfortunate tic.
His journey from relative normalcy, as a Pureblood with familial ties to the Ministry of Magic, to becoming perhaps the most loyal of Voldemort's Death Eaters is a complex one. Under the control of his father, and faced with abuse from his peers, Barty is dragged to the dark side by his ambition, a hunger for retribution, and his burning desire to do anything for the Dark Lord's approval.
 
Based on a combination of canonical information from the book and/or the movie, as well as headcanon.