Orphan refers to a page which neither links to other pages nor has other pages linking to it. Such stand-alone pages make navigation through the site more difficult. They also are more likely to contain articles which are off-topic for the site, or even be instances of vandalism. In addition, such articles contradict the nature and intent of a wiki structure.
While it may be possible for a topic to be so unique that no other topic quite relates to it, when you write an artcle, there should be at least one mention of a person, place, or thing that is or can be described in greater detail in its own separate page. In that case, you should have a link for it in your article. In turn, your article should also be of enough relevance to Doctor Who that at least one other article can be linked to it.