There are many naysayers regarding the new character in Season Eight of Doctor Who, Danny Pink. Not helping matters is the colorful last name, nor the fear of changes in dynamic that a new companion can bring after all, sometimes additional companions become third wheel characters, serving little purpose except to annoy. The original series' character Adric serves as an example to both a useful character (as a more innocent, less knowledgeable foil to Tom Baker's Doctor, serving as someone to which the Doctor can explain things) and as a useless appendage (as a wasted character, badly written as companion to Peter Davison's Doctor). Before going any further, every new major character since Patrick Troughton himself (and possibly before) brought worry to fandom, with some people worried that the show would suffer for the addition; that the show got cancelled once has heightened that worry, to the point where it has practically become a tradition for fans to freak out when a new regular character has been introduced. There are at least ten ways this character could fulfil a valuable role in the series, and viewers can be reasonably confident that somebody involved with the show will want to find a way to make this work.
10. Danny Pink Is An Alien
It is not the first time humanoid aliens have been on Earth. Consider Turlough, from the original series, apparently politically exiled from Trion to Earth. It could be that Danny took the name as a poor choice, much like Ford Prefect from "The Hitchhiker's Guide to the Galaxy." Aliens have long had a reason to visit the planet, whether in exile or coming for sustenance... or even to enlist the being known to be Earth's Protector, The Doctor. One of the more interesting answers would relate to Coal Hill School Itself: he could be a beneficent alien here to slowly accelerate human progress by educating the children well. It would be interesting to encounter such a benign race in an otherwise dangerous universe, and it would certainly help drive plots. It is notable that with recent changes to the Zygons in "Day of the Doctor" that Danny may actually be one of their race who has found a way to stabilise form; with the new accord in place there would be plenty of reasons for them to peacefully assimilate, or even possibly be welcomed in as members of U.N.I.T. for their ability to shape-shift and help with covert investigations. In fact, this may even tie in with a version of the next possibility...