Cartmel Masterplan
The Cartmel Masterplan is a fan conceived term to describe the development of the Seventh Doctor's tenure over the last two seasons of the original Doctor Who series and an attempt by script editor Andrew Cartmel to restore The Doctor's mystery, ultimatley hoping to explain his origins in a future story (Lungbarrow. ultimately never produced, but later written as a novel)
The Clues
The Doctor was tied into the pasts of Rassilon and Omega, hinting in Remembrance of the Daleks that he and they had problems with the prototype of the Hand of Omega before correcting himself, stating to Ace only Omega and Rassilon had difficulty. An un-aired, but filmed scene also has The Doctor reveal to a boastful Davros he is "far more than just another time lord". The scene was cut due to John Nathan-Turner not wishing The Doctor to be portrayed as a god in case it offended people with religious beleifs.
In Silver Nemesis, Lady Peinforte drops hints that she knows the true nature of The Doctor, but her obsession with the Nemesis Statue and it's power drives her to merge with it, she is killed destroying the Cybermen's approaching fleet.
In Battlefield, Morgana identifies The Doctor as Merlin, the wise sage and mentor to King Arthur
An unfilmed scene from Survival featured The Master, suffering from apparent amnesia, challenging The Doctor's identity and true nature. The Doctor argues that we must all "evolve" in some way.
The Unknown Future
Had a twenty-seventh season been developed, Marc Platt's Ice Time would have revealed that Ace had been trained by The Doctor to become a Time Lord, her rebellious attitude helping to reshap Gallifrey's policies and role in the safeguarding of time and space. Ace's storyline has met with various endings in both the books and comic strips since then (being killed off in the strips, and becoming a renegade time traveler in the novels). Ace remains with The Doctor in the Big Finish audio adventures alongside an additional male companion, Hex.
Following Ace's departure, other storylines allocated for the season would have had The Doctor gain a new companion as a favour from a former cat burgler-turned-aristocrat he would help out in a serial prior to this one. The intended finale of this twenty-seventh season was to have been "Alixon", a story which may or may not have seen The Doctor regenerate into his Eighth incarnation and saw the departure of Mccoy.
Legacy
The Cartmel Masterplan the comics which Cartmel scripted for Doctor Who Magazine, beginning with his debut story, "Fellow Travelers" where we find out at he has maintained contacts with humans on Earth for years and even has purchased a house there. The more sophisticated and mature New Adventures line from Virgin took the the Doctor in a more morally ambiguous, unreadable character who has extensive powers and an unknown history. Fans nicknamed the Doctor in his period as "the dark Doctor" or the "arch-manipulator". The novel Lungbarrow, the final Seventh Doctor novel, written by Marc Platt revealed the Masterplan in detail, however. Future Doctor Who producer Russell T. Davies had by this time contributed to the New Adventures series.
The current theme of the Tenth Doctor as "the Lonely God" seems definitely influenced by the Cartmel interpretation. He clearly has great, unknown powers, as when the god-like Doctor manifests using the Master's Archangel Network via the power of people's prayer in The Last of the Time Lords, among other instances of his having deity-like powers.