JafarSenpai
When Lex Luthor captors Wallace West, the Flash, despite not knowing who he is, he experiments on, tortures and imprisons the Flash, turning him into a pet. The League begin to fear it's too late for him when they bring him back; that what little bits of sanity the speedster was able to cling onto might be gone.
Warnings: Bruce x Wally, torture, gayness, rape/noncon, gore, forced cannibalism, etc.