" There's nothing wrong with a van. I once saved the universe with a big yellow truck!"
By my reckoning, Mickey is a companion, but not a very impressive one. I saw a comment once that compared him to Fourth Doctor companion Harry; it fits. "Mickey the Idiot" has good company in Harry "the Imbecile". Both played second fiddle and straight man while their female counterparts remain the focus of attention.
But unlike Harry, Mickey came on because of his girlfriend. His role as clown was established in the Doctor's response to his request: "Right then, I could do with a bit of a laugh." Mickey does loosen up a bit by the end of end of season two, and has developed into a serious warrior by the season four finale, but in the end, I never moved beyond feeling sorry for him. Rose treated him carelessly, not really caring about how her disappearance affected him. His marriage to Martha comes as a bit of surprise, but they were both hurt by the Doctor and Rose's romance...maybe they bonded over that. Not hate exactly, but...well...
okay, shutting up now. No fanfic recommendations.