The Doctor loved Donna Noble, she was smart, feisty, brave, funny, and generally amazing in every way, but he also envied her, because she had something he wanted; red hair.
Here he was, well into his tenth regeneration, and his hair had been dark brown, light brown, blond, even white, but never red. He’d wanted to be ginger for ages, but sadly had no idea how to influence what he would look like after regenerating; it was all a bit random.
Still, the next best thing to being ginger was travelling with one. He was having the best fun ever!