Dostoevsky's Memoirs from the House of Dead is a good companion to Gulag Archipelago to show how things got worse into the full medieval sadism in less than a hundred years.
Besides the gulag is a blueprint to basically all the forms of how totalitarian societies treat their subjects, especially if you can see the pattern working in less cruel and plausible forms.
Besides the gulag is a blueprint to basically all the forms of how totalitarian societies treat their subjects, especially if you can see the pattern working in less cruel and plausible forms.