The Doctor (Doctor Who)

The Doctor is a canon character from the long running TV show Doctor Who

In Badfic
Despite all Doctors having quite distinct personality characteristics and a unique sense of style, it is not always possible to tell from the story which Doctor the story is about. With one exception:

Classic Who
Doctors One through Eight have not much to suffer from Suethors, both because they are not as well-known to young fans and because they are not as young and attractive as the latest two Doctors. Doctor number Five however often features in slash stories with his companion Turlough, or three in a bed romps with his female companions Nyssa and Tegan.

New Who
The same cannot be said of Doctors Nine and Ten.

The Ninth
Despite a face apparently made of rubber, until recently Nine featured in many badslash stories, paired with Captain Jack Harkness. He also appears in saccharine depictions of mundane domesticity, although these usually, though not exclusively, gestate Nine's precocious brats within Rose Tyler rather than Captain Jack.

The Tenth
The pretty one -- if you go for the skin over bone type of guy -- is often paired with his companion Rose. Many fanbrats believe that she is his Twu Wuv. Easily forgetting, or perhaps not even knowing, that The Doctor has had many incarnations before RTD pumped new life into him, and consequently many companions. Uncle Rusty inexplicably failed to marry off the two of them and knock up Rose before the events of Doomsday, and so authors have been forced to either simply ignore the events of the season two finale, or else come up with a plothole-riddled explanation of how Rose returned from Pete's World to settle down and have the aforementioned precocious babies. Whatever the circumstances, however, Doctor-Rose ships often involve heavily Sueified canon characters. These fics have increased in number since the BBC announced that Uncle Rusty is indeed the world's most successful Suethor, and will be returning Rose to English screens in series four.

There are also stories where the Doctor for some reason does not have a companion and meets a girl (typical age range: 13 to 16 Earth years) who is in desparate need of being rescued. He helps her out and she becomes his companion. This companion is almost invariably a Mary-Sue.

The Doctor's Daughter
Hints in the new series that the Doctor was once a father have spawned many fics involving the Doctor's daughter, who miraculously survives the Time War with little or no explanation. Despite being a Time Lady, she typically has the demeanor and interests of an Earth teenager and none of the Time Lords' sexual restraint. She often attracts the romantic interests of male canon characters such as Captain Jack Harkness and the Master (who will of course be turned good by the power of twu luv).

Given that the first companion of the First Doctor (Susan Forman) was referred to, both in the scripts and in the publicity material, as his "Granddaughter" the idea that the Doctor has a child of some sort is perhaps not that farfetched!