Hey! I've been reading a lot of DW fics lately, and I gotta say I really love your take! Especially considering Celeste is a linear companion, I find that making things original when everyone knows what's happening next is tricky and you managed it really well! I love Celeste and how calm and collected she gets over time, and the twist on Rose's character you did was so in-character I didn't notice at first? And when I did, it was like "yeah, I can see this escalating" because the fact of the matter is Rose IS 19/20, and she does get super jealous and defensive, and she does have a bit of a wandering eye regardless of who she likes. Having Rose as a companion is like being back in high school, and the way you handled her, and balanced and contrasted her with Celeste is really great!
Another thing I enjoyed was the gradual relationship between her and the Doctor. It's smooth, and sweet, and not all at once falling into a relationship! That part where he found out she knew his future and they were a little more distant was perfect! I mean, sad, obviously, but it made it more meaningful when they became buddies again. Also I was totally waiting for him to confront her about it because she was kinda obvious about it in The End of the World?
I think it's a good decision, both as a writer, and for your readers, to not write out all the episodes, because rather than just telling us "these things all happened exactly the same as canon" and buffing up your word count, you focus on the character development bits, and make it easier for us to pick out what's changed and all the implications of that!
Tardis characterisation! Love it! So cute, honestly, doesn't feel cliched at all, and the POV sections worked super well. It felt natural, and also amusing, so well done!
Lastly, the slow build of Celeste as a companion, and disguised Time Lady is working so well! Like she starts off giddy and reckless, until it kinda sinks in that this is her life now, and there are real consequences. There's no sudden "oh this is a person and their dead body is in front of me" realization, she just gradually comes to terms with things a little at a time. And by this chapter, she knows her information has one giant blind spot, so she's not guaranteed to survive anything, but she has faith in her best friend to do everything he can to keep her safe, so she's gonna do her best to help him out and keep calm and nudge him in the right direction when she can. It's so sweet! And the slow-build Time Lady reveal, man, if you come back to this story I'd be sooooo keen to know when you plan to time that!
Thank you so much for sharing this story, if you ever plan to continue it, I'd be absolutely delighted, but if not I've still got 19 whole chapters here to enjoy! Have a wonderful day, hope you're safe and healthy. Thanks again!

So Celeste didn't try to stop the Doctor sending her and Rose away but she managed to get back to him without ripping open the heart of the TARDIS with a vehicle. Rose was very angry when Celeste left in the TARDIS and when they came back after the Doctor's regeneration.

I thought the bit where the Doctor was talking about only wanting a quiet life was sweet when he thought of Celeste. He was really angry when he thought Celeste was dead and then happy again when he found out she wasn't.

That was different, there aren't many stories where an ox gets turned into one of the gasmask zombies. The Doctor really didn't like being separated from Celeste and was very happy when he found her again.

I loved the way you did the aftermath of Father's Day in the TARDIS point of view, it was brilliant. Nickname wise Rose us the annoying blonde, the Doctor is the thief and Celeste is the favourite child. Rose really is jealous of Celeste even though Celeste is trying to be nice to her. Celeste is good at getting the Doctor to calm down when he's stressed.

Loved this fanfic until you explained how ‘giddy’ Rose was at Celestes death. No matter how jealous Rose is.

Rose would never be so shallow, she would never be happy about someone’s death Celeste was her friend once. So don’t you dare tell me that Rose is ‘giddy’. Rose has never been so inconsiderate. She was the most human and caring in the first season she would never!

Love, love, love. Why have you not updated?

I love the banter between Celeste and the Doctor, it's so sweet. Also the Doctor didn't mention Rose when he said he only takes the best.

So many differences to the original episode. I can understand why the TARDIS locked Celeste inside. She could probably see that if Celeste had gone out she would have replaced Rose from getting trapped with the Dalek which the TARDIS didn't want. Can already tell that the TARDIS is very protective of Celeste. Interesting that when the Dalek spoke about the Woman the Doctor loves he thought of Celeste.

Brilliant chapter, I love that Celeste saved them from downing street. I'm glad the Doctor's anger at Celeste didn't last long, it seems he values their friendship too much for that to happen, which is good.

Interesting that Celeste got a key to the TARDIS before Rose. This is probably when Rose's jealousy starts growing. Also never read a story where an oc didn't go to downing Street with the Doctor and Rose.

I love the original bits at the start and end of this chapter. So many changes that Celeste is making. It's nice to see the friendship between the Doctor and Celeste growing.

And now we have the start of the friendship between the Doctor and Celeste.

So Celeste takes Rose's place in the burning room after being knocked out.

So Celeste has already changed a few things in the plot. The big thing being that she saved the Doctor instead of Rose.