I've been biting my tongue about this til now but the football team chat is making me think about it. I used to have BPD (not anymore, after years of unsuccessful counselling it decided one day to
duck off of its own accord - not sure that's supposed to happen but it's coming up on three years now, so
) and like someone else said on a previous thread I find Jack fascinating because so many of her behaviours remind me of my own.
Not having a strong sense of your own identity and trying to steal bits of other people's, but being completely unconvincing because you're not really committed to them like an authentic person would be. Getting way too attached to people way too quickly and a total inability to be happy alone. Scary random outbursts of uncontrollable rage, followed by shame and attempts to backtrack. Making yourself into a victim to try and guilt trip whoever triggered your anger. Trying to present more masculine because you're ashamed of your out of control emotions and having them is seen as a stereotypically female trait. Even trying to diagnose yourself with all sorts of other issues that might explain your behaviour but are seen as less shameful than BPD - I'd have found it much easier to tell people that I was an alcoholic than "actually I'm just an emotionally unstable, chronically needy person who's entirely reliant on others for my sense of self, thanks for asking".
In my case I was extremely lucky that none of this ever happened publicly and even most of my best friends never saw the worst of it. I only told one person about it IRL and it wasn't until after we'd been very close friends for over five years. But I can easily see how if you had a public platform it would be really hard to stop it spilling over.
I'm not trying to diagnose her based on tweets or anything because obviously that's not how it works, and also there are many other conditions that can be mistaken for BPD, notably autism in women. So it's entirely possible that she shows similar traits for a different reason. I just find it striking how strong the similarities are.