ooh lots of intriguing things here... tell me about accidental baby acquisition? :D
Started writing this as a response to my @keepfandomweird bingo card and the prompt, you guessed it, 'accidental baby acquisition'. And, I asked myself, who would be the best, the funniest possible pairing to accidentally acquire a baby? And I answered myself, why, obviously Six and Ainley!Master.
Baby mysteriously shows up in the Master's TARDIS and the Master is alarmingly happy to play at being the creature's father, all tutting at the Doctor about best practices and sneering at the Doctor's clumsy, oafish attempts at handling the child, tch. The Doctor is ALARMED by this. And deeply irritated. And definitely not charmed. At all.
The Doctor was beginning to develop a distinct paranoia that the baby had somehow been the Master's doing. However unwise their occasional trysts— and while he was perfectly willing to concede that they were unwise, that was somehow never sufficient to stop him actually engaging in them in the moment— the Doctor had at least been under the impression that there was no danger of accidental procreation. Other species might need to worry about contraceptives; the Time Lords had done so much fiddling with their own genome over the centuries that it was virtually impossible to accidentally conceive a child.
Obviously, in this instance, neither of them had literally conceived the child, but it had been two weeks, and the Master was showing alarming signs of contentment with fatherhood. It would be just the kind of byzantine plot he'd concoct.