CGB Zach's Space

A cat is a small creature in the middle of the food chain that is fully aware that you are a very large thing that could stomp its head in at any moment and yet it chooses to rest its tiny little head on your leg for a nap and spreads out on the floor near you exposing its belly and its most sensitive organs. It brings dead mice and bugs to you to share food.

Don’t you get it? This tiny thing trusts you. It wants to help you too. It licks your leg thinking that it’s helping. It kneads on you to find comfort. It shares its body warmth with you in the cold and gives you your space in the heat. It hisses at other mammals it sees outside including other cats in an effort to protect its family.

step two: in your diffidence, leave many half-drunk glasses of water around your apartment

step three: your cat, who is stupider than any other mammal on earth, living or dead, starts drinking from your many abandoned water cups

step four: the cat now believes these are for her

Ace: I've nevrer asked - how do you manage to attend our meetings when you spend all your time trekking through the Amazon and are banned from most private airlines?

Jo: Oh, well, TARDISes make quick work of the Atlantis.

Mel: So he still comes back for you, after all this time?

Jo: I don't think he'd ever have the heart to abandon me. I suppose he misses when I worked at UNIT and saw him so much more often.

Liz: It was fun, being with him and UNIT, wasn't it?

Jo: Yes, it really was. I think he's quite a lot bark, but he never did have all that much of a bite.

Martha: Oh, your one had a bit of bark, did he?

Jo: Never at me, of course! He was always a charmer when it came to me.

Tegan: A charmer. Sweet. That lines up with how I remember him.

Jo: I know! But nobody ever took me seriously when I said so. Nobody at UNIT apart from me ever really saw the Master the way I did.

Why Jenny, Not Jack

Hot off the revelations that the Doctor's past isn't what she thought it was, along comes a piece of the Doctor's past that she had rejected and lost. Inexplicably alive and there to rescue her. Yes, also Georgia Tennant calling Jodie Whittaker "Dad," but that's just for consistency and our lovely cold open.

Also Jack got his cameo last season. Keep moving forward.

For a Doctor as closed off as Thirteen at this point, Jenny is another person who can be easily explained and also make Graham's eyes pop out of his head. Plus between Jenny and Yaz and the fam's separation preparation, Thirteen might just have to verbalize some of her feelings--even if it is just 'sorry' or 'you were always my daughter.' Acceptance, or S12!Thirteen's version of it, continuing the Chibnall era's theme of being kind to what came before.

Throw in an oblique reference to the EU while we're there, since Chibnall's tenure began with Big Finish getting license to do modern Who.

As for the elephant in the room, aka Jack and Yaz having their chat about what it's like to love the Doctor, I think that's as easy as Jenny explaining that the Doctor is happier than Jenny's ever seen her and that's down to the fam/Yaz.

“Are you responsible for this box, sir?”