Ruby Sunday AU (Doctor Who)

If interacting the Doctor him and others: she's the God of Stories and therefore Weird Stories will happen, which Ruby can fix; not only she'll keep having adventures after leaving the Doctor, but every now and then a part of her that has meta-knowledge will speak, taking over, something Ruby can't remember when she's herself. People will try to tell her but she'll forget again.
To be clear, she KNOWS something is wrong, the 73 yards episode never fully left her head, and she assumes she must be some horrible thing if everyone who truly saw her ran away forever.

An excuse for her to still be the Doctor's part-time companion: she'll feel compelled to call him for some new adventures, especially because Ruby is finally allowed to have way stronger emotions, including negative ones, which she couldn't have earlier for Plot Purposes, and needs to change air. Also wishlist verse: she's destined to be Poppy's adoptive mom (Belinda was doing great and never indicated a wish for motherhood), and it's an older Ruby who remembers her and pushes the Doctor to give her the life she wanted back, not Belinda.  

Now, about the AU-ness: When the Doctor opens the door for all kinds of gods to come in, the GOD OF STORIES came through and made itself into the baby left at Ruby Road. The potential was just too good. This also explains all the strange things happening around Ruby. She could technically be an all-powerful being if she can create bubble universe, but the God of Stories isn't interested in that power, it would make things boring. It's a benign entity, and Ruby is very real, so she will be reborn with little changes because stories don't die. 

One of the ways to see the truth is to stand 73 yards away from her and really look at her. You are not supposed to see the 'full story', hence people's brain refusing to deal with it. The Doctor can get in control of his emotions like with the Boogyman, it's fine! But people instinctively will not look at Ruby from that specific distance unless Ruby herself (young or old) makes them. 

Also a canon divergence: while I do respect that some adopted kids will keep considering their biological parent 'their real parent', calling Louse 'my real mom' was a bit much, so to my Ruby they are both her mothers, Louise is her bio-mum, while Carla is just 'mum'.
Ruby is struggling with the fact that Louise never looked for her out of fear of Ruby hating her while Ruby was desperate to find her, and then struggles with feeling guilty over not being ecstatic, and that's true regardless of the fears that seem from the episode 73 yards.

How can she meet previous Doctors? She can become aware that a whimsical powerful - non malign - force is pushing her around to save people (but really, the god of Stories if just vibing and watching Doctor Who with us) and be sent to parallel universe, therefore not changing the current Doctor's history. She'll be an older Ruby and by then treat the Doctor as an old friend she already had many adventures with (well, not YOUR version, but parallel ones)