Even if she had said "no" and God put His plan in place despite her defiance she would not have been either a victim or "broodmare" as you put it.
You can't be a victim of God. And she would not have been a broodmare (no sex act involved) but a receptacle of Salvation to mankind.
Do you not understand omniscience? God leaves nothing nothing to chance. He knew before the beginning of time that Mary would cooperate fully and unconditionally. That is why He preserved her sinless.
Peace be with you.