BtVS/DW: Xander Harkness
Yes, this is yet another Xander's real family plotbunny. They're just so fun aren't they?
Anyway, the bunny that ambushed me is from what I understand in Torchwood Jack mentioned having been pregnant (Actually not the first case of canon mpreg in a show I've seen, that award goes to Red Dwarf actually). Well I had this thought of Jack as Xander's mom, and the Doctor, Nine I was thinking, as his dad.
Pretty much Immortal!Jack and the Doctor met at a bar, and Jack was more than a bit drunk, and the Doctor thought that Immortal!Jack was normal!Jack because he couldn't sense the whatever in Immortal!Jack because of something hiding it temporarily. Anyway they get freaky and the Doctor blamed normal!Jack's lack of memory on whatever he had been drinking the night before.
Immortal!Jack is having a "I should really stop jumping people that look like the Doctor when drunk and in bars" hangover the next day and neither really thinks much of it while thinking of it (mostly on the Doctor's end). Jack meanwhile, ends up pregnant and vaguely panicky because the twentieth century isn't exactly equipped to handle mpreg's, but he's a member of Torchwood, so he can blame it on what it is, his sleeping around and something weird that happened on a case that he didn't notice until he ended up, I believe the phrase is, "stuffed up"?
'Course due to certain physiological difference's between Time Lords and humans, Jack figures out pretty quick after Xander is born (or even at some point in the pregnancy) that the Doctor had to be the dad. So he would have been kicking himself for not realizing that it had been the Doctor.
Well all this happens before Jack's in charge of Torchwood Three I'm thinking, I had this weird thought of Ducky from NCIS as a former member of Torchwood that was still there when Jack got stuffed up, maybe even having been in charge. Although Xander did grow up in Torchwood (maybe even in the Hub of Torchwood Three) as a bizarre, but happy kid that scares a few aliens that he meets, and is adored by others.
Fast forward a lot of years, by the time the Torchwood series is going on Xander is at least in his teens and was sent away to school - by threat of mutiny - for the sanity of the people working with Jack, because Xander gets into just as much trouble as his parents. So the current crew of Torchwood actually have no idea that Xander exists. Jack never mentioned him, figuring that it's not their business, and Xander's busy being a terror at school (maybe working on how to be just shy of expelled, but never actually crossing that last line).
Then you have that whole year-that-never-happened thing happens and Xander shows up at Torchwood one day to smack his "Mom" around for being so stupid. Maybe have one of Torchwood somehow get a hold of the Doctor and telling him that Jack's son is visiting and threatening to sic his alien nanny on him for being so stupid. (I can see the nanny being the one being that Jack actually fears)
Then you having the Doctor showing up and having an "Oh my god that's another Time Lord" panic attack. And the Doctor being nosy manages to scan Xander and find out that not only is he Jack's son, but also the Doctor's.
Or maybe something having happened at school so he got sent home, or maybe got kidnapped by an alien admirer and had to steal a ship and make his way back to Earth. Either way Xander would show up grumbling about idiots.
Either way there would be a lot of "OMG!" reactions to Xander's showing up out of nowhere. | 
creative
drained
amused
cold![[info]](http://www.insanejournal.com/img/userinfo.gif){kind=small}
awake
thoughtful
scared
curious
hungry
crazy
annoyed