At first, I didn’t like Donna (played by the fantastic Catherine Tate). I had become really attached to Rose, and I didn’t want a new companion, especially not some shrill, obnoxious woman who didn’t trust the Doctor. By the end of the first episode, however, I could see that she might be good for the Doctor — she stopped him, if nothing else. But she didn’t want to stay with the Doctor (more fool her). So we moved on to the beautiful, talented Martha Jones.
Fast-forward a year or so — Donna’s out investigating suspicious occurances, looking for the Doctor. She’s very take-charge; she mostly holds her own against the Doctor. Donna Noble is a force of nature. I end up loving Donna. She is funny and adult and brassy and loud. She’s compassionate. She teases the Doctor and pokes fun at him in a sibling sort of way, but she also understands him, to a certain extent, like in the Library when she asks whether “all right” is special Time Lord speak for “not all right at all.”
Donna grows so much throughout her time with the Doctor. One of the most heartbreaking moments of the entire new Doctor Who (along with River Song’s death and Ten’s regeneration process) is the part where the Doctor wipes her mind of all memories of their travels together in order to save her life. I would have loved to see the Doctor and Donna travelling for the rest of her life; I think they were a marvelous pairing. Somehow, Donna has become my favorite of the Tenth Doctor’s companions. The idea that she will never join the Doctor for another adventure is a terrible loss for the show.