Okay I have searched for this Hellsing FF but can I find it? Nope

I can't remember the pairing but its based on the fight with Millennium

Seras and Integra are captured and Seras is attacked by Hans and held down by Dok, Walter and another soldier whilst they rape her, after wards Walter does the same to her

Walter eventually finds a way to free Integra and Seras but is drained by Seras in the process