Some thoughts about blackbright/phantomquill and hakanaki
There are a few ways to spin this trope
Firstly, let's say Blackquill never met real Fulbright. It was the Phantom from the start (of course Simon doesn't know that) Here hakanaki is caused by the Phantom not returning the feelings.
Now there are two options
Option 1: they don't get involved romantically - that's just the most basic form of hanahaki
Option 2: they do - now that's more interesting. Does the disease stop? Does it continue?
I think most common version says whether the disease is cured depends on if the victim thinks the love is requited. So according to that, if Simon believes that this is real then boom, problem solved.
(tho bonus points if during turnabout for tomorrow hakanaki comes back. Beautifully tragic)
However, it's a fictional disease, we can make it more angsty. Let’s say it has some divine knowledge of how genuine the feelings are.
So it all seems well, they're dating, or at least have something going on between them, but the flowers don't stop because the Phantom's feelings aren't genuine. And Simon doesn't know why the flowers aren't stopping, why is it getting worse, he starts doubting "Fulbright"s feelings, making everything worse in the process. There's probably a big emotional scene at one point. And the Phantom is just panicking because shiiiiiiiiiiiiiiiit
Now let's assume Blackquill met the real Fulbright, at like the very beginning. Then he gets hakanaki but doesn't know yet, and Fulbright gets replaced.
I was going to say at first that this is a more interesting option, but now that I think about it, the outcome is almost the same because option 1: no romantic involvement - most basic hanahaki stuff and option 2 is again, if based on Simon's beliefs then it gets cured, but going with the "the disease has divine knowledge" once again, it's not cured and Simon is doubting everything and so on the only thing that changes is the cause, because here I'd say it's because real Fulbright doesn't return his feelings
Both of this scenarios work when Fulbright is dead, but let’s add the Bobby lives AU, just for the fun of it.
In the first one he actually does nothing really.
And in the second one, the only reason for him to be alive is to have a happy ending, where he gets rescued and they fall in love and Simon is cured yippie
..or is it?
Because what if real Fulbright doesn’t love Blackquill back?
It is admittedly kinda the same as basic hanahaki in the end, but I am an enjoyer of taking a Bobby lives au and making it tragic
Bobby is alive, but it turns out he doesn't have feelings for Simon (especially angsty if the Phantom got involved romantically with Simon) just with addition of flowers
Or what if Bobby lives, but Simon realizes that he doesn't like real him this way (and it drives him absolutely insane that he was/is in love with the Phantom)
in context of hanahaki we're back to the first scenario, of it being caused by Phantom not loving him back
And while on the topic of hanahaki, there's also versions of getting it surgically removed, but losing your feelings for the target in the process, and I just think Simon would absolutely get it done.
Unfortunately, he's in prison womp womp