To save her in order to use her as Voldemort used Bellatrix, to bind her to him with the bonds of love as Voldemort did, because she was a powerful witch to be used as a tool.
Hence the bloodthirst comment.
To save her in order to use her as Voldemort used Bellatrix, to bind her to him with the bonds of love as Voldemort did, because she was a powerful witch to be used as a tool.
Hence the bloodthirst comment.