By the time Plath wrote "Daddy," her faith in the inevitability of this violent sexual dynamic apparently remained firm, but her attitude toward her place in this relationship had changed. Tragically, she still cherished the notion that masculine sexuality was the perfect emblem for power ("Every woman adores a Fascist") and that she was doomed to sexual and social victimization ("I think I may well be a Jew" ), but in "Daddy," she appropriates that power for herself or for the female voice in that poem, and she does so in sexual terms. She becomes the rapist who terrifies, who imposes himself upon others, who makes his imprint - both poetic and psychological - upon reality. She no longer hides because she no longer has to. She has shed the femininity which threatened to undermine her The existence of the poem itself, addressed to "Daddy," demonstrates that her silence has been broken, that the father who has rendered her speechless has lost his ability to erase her: "I never could talk to you. / The tongue stuck in my jaw" (223). The act of speaking, thus, is her first appropriation of the father/lover's power.
Both of the men against whom the voice rails in "Daddy" have committed crimes against the speaker's heart: Daddy is the one who "Bit my pretty red heart in two," and the lover who serves as a replacement for Daddy "said he was you / And drank my blood for a year." Thus the female subject's revenge must be structured similarly: she has killed Daddy and his representative ("There's a stake in your fat black heart" ) by means of a figurative rape. She thrusts a deadly force through Daddy's evil center, his source of power over her, his heart. And the very fact that she speaks constitutes a violation of Daddy's privilege and power. Plath here reverses the metaphorical expectations and writes a poem that is overwhelmingly powerful but also unsettling since the speaker of the poem does not undermine the system of control which violates her but rather turns the tables, accepting this gendering of violence as inevitable. If she will no longer be victim, she must become victimizer. If she will no longer be raped, she must become the rapist. If she will no longer subject her bared self to violation, she must herself become violator.
From "The big strip tease: female bodies and male power in the poetry of Sylvia Plath." Contemporary Literature 34.4 (Winter 1993)