Disclaimer: How I wish I owned them! Anyway, I don't; they're the property of the BBC.
Beginning of the Thaw
She thinks about refusing before realising she can't, and goes to the archive.
The Guardian told her she could learn something from the Doctor – but after she's gone through what records they have, she's not sure what. All he seems to have on her is years; years mostly spent away from Gallifrey, gallivanting around the universe causing no end of havoc, so far as she can see. He hasn't been home for any decent period for centuries, relative time. He drives an ancient, obsolete Type 40 TARDIS that he appears to have stolen, is already on his fourth regeneration and has a tendency to pick up companions from primitive planets. Indeed she has already met his last passenger, who has shocked everyone by bewitching a Time Lord into a relationship. The very presence of Leela on Gallifrey is quite clearly the Doctor's fault, and Romanadvoratrelundar finds herself fascinated and horrified at the same time.
She would be the first to admit that she does not understand the Doctor, nor why the Guardian has picked him for this impossible quest – nor, indeed, why she should be the one to join him. But armed with her new knowledge of him she slips aboard the Doctor's TARDIS whilst the Guardian is giving him details of the mission, and explores thoroughly. The machine is, as she expected, dilapidated and battered and ancient, but well-cared for. She can see that much. And she can also tell the TARDIS has a certain ... affection for the renegade. It's there in the hostile thrumming of engines as she comes aboard and the protest as she finds a room and deposits her few belongings in it.
Once she's settled in, she returns to the console room and prepares the place for the Key's core before he arrives. She's feeling uncharacteristically excited about the time ahead. It will be her first time off-planet, her first time travelling anywhere. It's an opportunity she's determined to seize. So when she hears the doors open to admit the Doctor, she stands tall ready to greet him. The very beginning of a new world.