Cassy, Legree’s literal sex slave, is a minor but important character who gives Stowe an opportunity to suggest, with a few broad strokes, the extent of the sexual mistreatment to which female slaves are subjected.
Nearly ten years after Uncle Tom’s Cabin was published, former slave Harriet Jacobs wrote her autobiography, exposing the scope of sexual abuse of black women by white slave owners. In 1852, this was still a relatively unusual subject. It wasn’t a secret by any means, but it wasn’t usually talked about.
Stowe makes something of an exception in her otherwise sentimentally whitewashed novel by describing Cassy’s past as, first, a common law wife, and then as a sexual slave. Even so, we learn about Cassy’s suffering in flashbacks – it doesn’t happen "onstage."
Cassy is a contradictory and fascinating character. She’s a slave, but she has pride and noble bearing. She’s hardened to her suffering, yet she takes innocent Emmeline under her wing. Legree can force her to work in the fields, but she has a lady’s convent education. As a "quadroon," or someone who is one-quarter black, she’s already in a strange in-between position in the racially charged South. She’s been cast off by Legree, who intends to replace her with fifteen-year-old Emmeline, yet she still maintains a strange fascination and power over her master.
Like George Harris, Cassy is a realistic and rounded character, though a minor one. She wants to be virtuous, but she is bitter and despairing as a result of a lifetime of betrayal and sexual abuse. She considers murdering Legree, and nearly does so at one point. Yet she is also influenced by Tom’s piety and faith, and she cares for Tom after he’s been beaten.
Inspired by Tom’s nonviolent resistance, Cassy concocts a clever strategy to save herself and Emmeline from Legree’s perversions – they actually hide in his own house, in the supposedly haunted garret. When Tom is whipped and beaten to death because he won’t reveal their hiding place to Legree, Cassy risks everything to visit him on his deathbed.
Of course, at the end of the novel, we discover that Cassy is Eliza’s long-lost mother, and Cassy and Emmeline join the extended family of the Harrises. In this case, Stowe sacrifices realism for the sake of a sentimental family reunion – but she also suggests that a small amount of domestic support can counteract a lifetime of abuse.