Geminus Nebula is a variation on an idea I’ve had for some time, in which The Doctor and Jack would talk about the reason why Jack is immortal.

I first started writing about Jack Harkness in the Ninth Doctor’s world back in August 2005, before there was any hint about Torchwood and Jack having a life of his own separate from The Doctor. So from there on there were always two Jack’s in alternative universes, one who went off with Hellina Arturo of the 22nd Space Corps and got promoted, and the other doing his think in Cardiff. But since they both had the same experience aboard the Gamestation, it stands to reason that they would both be immortal. I’ve never actually done a story that tests that theory in the New Lords of Time series, and I probably won’t. I’d rather keep that for the Torchwood series. But this story at least fills in some blanks and explains why Jack is how he is.

It also goes some way to explaining why he and the Face of Boe are one! Jack is immortal, but he has admitted to a few grey hairs, a slow progress of his age. The Doctor explains in this story that he will age according to how he feels. If he feels young, he will stay young for a long time. But The Doctor knows that eventually, he will become so tired of living that he will not only age but evolve – or devolve – into the Face, presumably in much the same way that The Doctor devolved into the strange midget that The Master kept in a bird cage in Sound of Drums/Last of The Time Lords. Obviously Time Lord DNA does odd things when it doesn’t regenerate in the natural Time Lord way.

The reconstructed locations that they pass through on the journey to the centre of the Nebula are partly taken from Doctor Who history – Limehouse and the Albion hospital, and Pompeii, where Jack claimed to have worked one of his cons. Omaha Beach in the Normandy landings and the battlefield at Cex-Law are my own inventions. The former was in my mind because I’d been watching the D-Day anniversary commemorations on TV. Of course, it would be Omaha since that was one of the beaches the American army landed on, and Jack is, nominally at least, an American. Cex-Law was my attempt at a fictional battle on another planet which would be as nasty and dirty as those D-Day landings or the fields of Flanders in WWI. The creatures that attacked Boeshane have never been named, of course. Jack describes them as being the worst creatures you could possibly imagine. I have always avoided naming or describing them in case anyone plans to do so on Torchwood at any time. But I keep in mind the ‘bugs’ in the Starship Troopers films. The way Jack speaks of them and the attack on Boeshane sounds very like the kind of war between Human and arachnid in that film. The idea of Jack as a young man wanting to get revenge and signing up to fight a battle that turned out not to be very glorious at all was compelling. It needs telling over and over that war is dirty and nasty. Wars DO need to be fought sometimes. Even The Doctor recognizes that reality from time to time. But nobody should imagine them to be glorious.