Disclaimer: Doctor Who belongs to the BBC. Abigail belongs to me.
"So, Doctor, where are we off to now?" Abigail asked, leaning against the rail as she watched the Doctor fiddle with the control panels.
"I dunno!" the Doctor replied, looking up and grinning at her. "Thought maybe we could go to the future this time 'round, since we went to the past yesterday."
"Future sounds fun. With aliens?"
"If you want!" The Doctor ran to the other side of the controls and flipped several switches. "What say you to the Isop Galaxy?"
Abigail came around the rail to stand next to the Doctor, who was watching the monitor with a look of utmost concentration. "Wherever you think is best." She hesitated. "Doctor, do you think this is going to be alright? You're, well…" She hesitated, then gestured at the Doctor. "You're different."
"Different?" The Doctor snorted. "Why should things be any different just because I've regenerated? Nothing's changed: it's you and me bouncing around the universe, through space and time, seeing the sights, saving people, just like always. I'm still the Doctor, and you—" She bumped her shoulder against Abigail's. "—are still my Abigail."
"I suppose so." Abigail looked up at the time rotor, collecting her thoughts.
The Doctor laughed and danced around the console to type in coordinates. "Now, if I'd grown another head, then we'd have cause to panic…"
"That's possible?!" Abigail's eyes went huge.
"Anything's possible, really. Look at us! Making impossibilities happen all day!" The Doctor pulled a lever, and the familiar noise of the TARDIS echoed around the room. "And we're off to do it again! Once more unto the breach, dear friends!"
A/N: Because why should it matter if the Doctor's a woman or not? It's well-established canon now that it's not unheard of for Time Lords to change sex upon regeneration. It'd be natural to them.
And, well, underneath it all, the Doctor will always be the Doctor, no matter what. Which is why the story ends here; after the initial reaction, there won't be much else that'd be different. She'll keep doing what she always does: travel space and time, and save the universe before running off to do it all over again. She'd just be doing it with a new face.
Thanks for reading!
-Dndchk