Every member of the TARDIS crew in the two series played a part. The Doctor was the brains. Captain Jack was the brawn. Rose was the heart. And Mickey... OK, let's face it. Mickey was the tin dog that was more trouble than he was worth. The character was introduced, together with Rose's overbearing mother, as a symbol of the humdrum, dead-end life she was escaping by joining the Doctor. The fact that he eventually joined them on the TARDIS meant that this same mundane reality was invading the fantasy and escapism of the Doctor Who universe. Making Mickey a companion was like making an accountant a member of the Avengers. And because he was so totally in love with Rose, it made the blossoming romance between Rose and the Doctor just a little bit more uncomfortable. It was like having a sad, whimpering puppy in the background of every scene. Even after acknowledging that he was just the 'tin dog' of the group, he did little to improve the situation. Yes, he saved a child by crashing his car through the school gates. Yes, he shot a Dalek in the head with a ray gun. Yes, he took on a hoard of Cybermen on a parallel Earth. But despite his best attempts, Mickey was unable to break out of his original role, and remained a character that was at best pitied and at worst hated by pretty much everyone who watched the show.