A Seventh Doctor who didn't regenerate retired to live on a world similar to ours, where he spends his days looking after woodland creatures, and is known by others as the wizard Radagast.
I know this is in response to this post, but it makes me think about how … kinda frustrated I am with 7′s character development. I’m probably just bitter that Steven Hall’s 50/50 was never made, but Big Finish and the Virgin novels so thoroughly teased a dark, manipulative, maybe even evil Seventh Doctor, and it’s pretty disappointing to me that they’ve kind of backed down from that.
Of course, the big problem is the regeneration continuously looming over 7′s head. 7 regenerated long before his story was finished, and the few glimpses of 7′s personality in the TV movie are sort of hard to reconcile with the master manipulator persona. From Lungbarrow to Doom Coalition, writers have been trying to tie into that version of 7 for decades, and I think it limits the storytelling opportunities. If we already know 7′s endpoint, both physically and character-wise, where else can he go?
I think there’s a solution to this. We already know that 7 found a loophole in his fate and went on a ton more adventures even after the Time Lords sent him to pick up the Master’s ashes. But what if we pushed this one step further? 7 finds out about how relatively useless his next self is going to be, and, to stop them from screwing up all of his plots, he wipes his memory shortly before the TV movie. This would give us an “unbound” 7 who would be able to keep developing naturally without worrying about the future he’s supposed to eventually have.
… I’ve been thinking about this idea for so long that, even if it’s never implemented in any form, I think I’ll always imagine that 7 went on some crazy adventures before wiping his mind in the end.
All the (canonical) Doctor's companions and how they arrived and left
Surnames in parentheses were not shown in canon.
Ian Chesterton & Barbara Wright: Found the TARDIS in Totter’s Lane, entered it and got swept up in events. Returned home via a Dalek time machine.
Susan: Evidently the Doctor’s granddaughter. Left behind on a future Earth after a Dalek invasion to marry a local soldier.
Vicki (Pallister): Rescued from the planet Dido, left to marry Troilus and became the Cressida of legend.
Steven Taylor: Stowed away on the TARDIS when he found it on a planet he was marooned on, left to help govern a society of savages.
Katerina: Joined the crew after meeting them in Troy, sacrificed herself to save the Doctor and his other companions.
Sara Kingdom*: Encountered the Doctor on a mission to stop the same enemy, aged to death by a Time Destructor.
Dodo Chaplet: Stumbled into the TARDIS, left to recover after a traumatic psychological attack.
First and Second Doctors
Ben Jackson: Curiously entered the TARDIS in London, decided to leave when the TARDIS returns to his home time period.
Polly (Wright): Curiously entered the TARDIS in London, decided to leave when the TARDIS returns to her home time period.
Jamie McCrimmon: Followed the Doctor to escape Redcoats in 17th-century Scotland, returned there by the Time Lords with his memory erased.
Victoria Waterfield: Orphaned by the Daleks and ‘adopted’ by the Doctor and Jamie, decided to live with a childless couple who adopted her.
Zoe Heriot: Stowed away in the TARDIS, returned to her home by the Time Lords with her memory erased.
Second and Third Doctors (and others)
Brigadier Alistair Lethbridge-Stewart*: Met the Doctor as part of his job co-ordinating UNIT forces, never formally departed as his association spanned several Doctors.
Liz Shaw: Assigned to assist the Doctor in his role as UNIT scientific adviser, departure unknown (in non-canon, returned to Cambridge)
Jo Grant: Assigned to replace Liz as the Doctor’s assistant, left to marry a visionary scientist.
Third and Fourth Doctors
Sarah Jane Smith: Stowed away in the TARDIS investigating UNIT and the Doctor, left behind (in Aberdeen) by the Doctor when he was summoned to Gallifrey
Harry Sullivan: Assigned as a doctor to the Doctor, found himself in the TARDIS by accident. Rejoined UNIT to continue his work with them.
Leela: Demanded the Doctor take her with him from her savage homeworld. Left to marry Time Lord Andred on Gallifrey.
K9 Mark I: Given to the Doctor by his creator, Professor Marius. Left behind on Gallifrey with Leela.
K9 Mark II: Created by, or at least copied by, the Doctor to replace Mark I, left in L-space with Romana.
Romana: Assigned by the Time Lords to help the Doctor defeat the Black Guardian. Remained with him after she regenerated. Stayed in L-space to assist the newly freed Tharil slaves.
Fourth and Fifth Doctors
Adric: Stowed away in the TARDIS, killed when trapped on a freighter which crashed into prehistoric Earth.
Tegan Jovanka: Accidentally found the TARDIS, mistaking it for a real police box, left due to the violence of the Dalek Civil War.
Nyssa: Taken by the Watcher (some form of mid-regeneration form of the Doctor) to Logopolis, stayed to help a colony of diseased people find a cure after being infected.
Vislor Turlough: Ingratiated himself with the Doctor as part of a plot to kill him. Returned home after learning his dead brother was actually alive.
Kamelion: Freed from the Master’s control and asked to accompany the Doctor. Killed by the Doctor (on his request) to prevent him falling back into the Master’s hands.
Fifth and Sixth Doctors
Perpugilliam “Peri” Brown: Co-incidentally taken to the same planet as the Doctor by the Master. Killed by King Yrcanos when her mind was taken over by an evil genius, but pulled from the timestream at the last moment and lived on to marry Yrcanos.
Sixth and Seventh Doctors
Melanie “Mel” Bush: Meeting unknown due to confused time streams (she literally just appeared), left to adventure with conman Sabalom Glitz
Dorothy “Ace” (McShane): Helped the Doctor defeat the criminal Kane, invited to replace Mel and essentially switched places with her. Leaving details unknown but before the Seventh Doctor regenerated.
Grace Holloway*: Accidentally killed the Seventh Doctor while trying to save him from gunshot wounds, helped the Eighth defeat the Master. Left behind afterwards. Never actually travelled in the TARDIS.
Charley, C'rizz, Lucie, Tamsin, Molly: All apparently travelled with him at some stage. Details not explored in canon.
Adam Mitchell*: Invited by Rose to join, against the Doctor’s better judgement. Kicked out of the TARDIS when he attempted to use future technology to make himself rich.
Ninth and Tenth Doctor
Rose Tyler: Invited to travel after helping the Doctor defeat the Nestene. Sucked into a parallel universe through the Void. Returned briefly but eventually went back again to live with her new family there.
Mickey Smith*: Invited by Rose, her on-again-off-again boyfriend, into the TARDIS. Stayed behind to replace his parallel universe counterpart to fight the Cybermen. Returned eventually to fight aliens in the main universe.
Martha Jones: Invited to travel 'just once’ as a thankyou for helping the Doctor and remained. Left because she was in love with the Doctor, but returned briefly after she called him in to deal with the Sontarans.
Donna Noble: Asked to travel by the Doctor after they fought the Racnoss; refused, but changed her mind when she met him again. Became part Time Lord after a “metacrisis” and had to have her memory erased lest her brain overload and kill her.
Amelia 'Amy’ Pond: Invited to travel by the Doctor as a child but due to TARDIS navigation problems, had to wait more than a decade. Sent back in time by a Weeping Angel and lived the rest of her life in the past.
Rory Williams: Asked to travel by an uncomfortable Doctor after Amy tried to seduce him. Sent back in time by a Weeping Angel and lived the rest of his life in the past.
River Song/Melody Pond*: Daughter of Amy and Rory. Conditioned to kill the Doctor, fell in love with him and married him, travelling with him intermittently but not always chronologically from his perspective. Died helping the Tenth Doctor defeat the Vashta Nerada and uploaded into the Library.
Eleventh and Twelfth Doctors
Clara Oswald: Encountered the Doctor as one of a number of copies of herself scattered through his time stream. As of the mid-point of Series 8, still with him.
*Not always counted as Companions as they only travelled very briefly with the Doctor or highly intermittently.
Stowaways: 4 Accidental passengers: 7 Deliberate invitees: 22 Imposed from outside: 3 Deaths: 5 Voluntary departures: 18 Abandoned or evicted: 2 Lost or forcibly removed: 6 Males: 10 Females: 32 Humans: 35 Robots: 3 Aliens: 4