@Mithoron I appreciate that fans of Sanderson may want to respond to "What should I read to understand X" with "Everything!", but that is discouraging and intimidating for a casual fan of a single series. In short, I won't be reading everything.

Please focus on a single thing that Squealer could represent. It currently seems that you want two separate answers, one for history and one for modern society. Squealer likely represents at most one specific thing.

Welcome to Literature Stack Exchange, take our tour! Please read our identification-request wiki and, if any of the prompts there jog your memory, please edit further details into the question. For example, when were you in middle school? Was this a middle-grade book, or aimed at a different age? What language is it in? Where was it set, e.g. a small town in Ohio or a large school in Tokyo? What time period was it set in? Did it have other fantasy/sci-fi elements, such as aliens or fae? Do you remember anything about the cover?