You took my baby from me and hurt her. And now she’s all grown up and she’s fine. But I’ll never see my baby again.
One of the most chilling moments in Doctor Who comes from the look on Amy Pond’s face and the revenge in her voice as she openly defies any moral code she is expected to live by as the Doctor’s associate and kills the woman who kidnapped and tortured her daughter.
The most interesting thing here stems from the fact that River doesn’t know Donna or have any personal vested interest in her and yet she looks at her with such emotion. Donna doesn’t die traveling with The Doctor as the audience suspects in this moment. She forgets.
River has seen a lot of horrible things and isn’t one to be easily moved, but you can see how just the mention of Donna’s name completely affects her. The look on her face reflects the pain of what The Doctor told her about Donna. We are seeing a reflection of how much and how deeply what happened to Donna affected The Doctor long after she was gone.