She can do this, which is what Billie has realized. She isn't winning this fight. This time, rather than charging in again or trying to teleport somewhere for the advantage, she bares her teeth and hisses one last time, still bubbling with anger even as she bleeds out.

From there, it's an effort to move, but she still whirls around in the corner she's in and throws herself at the window instead. The glass already gapes open brokenly from some prior damage, meaning it's simple enough for a rat to get through, a little less simple for an injured one but a few more cuts and scratches from glass goes unheeded as she wriggles through to the outside.