Curate, connect, and discover
One thing that is now unfair to ask is...what is Nine's name? Look hori treated him as an afterthought but his lack of origins works better than the comical twnko's origins.
Yes his family was all killed thanks to him but ...I can't help to think that scene was too ridiculous.
We never saw anyone mentioned them again, not even shig. (He remembers them in MVA and we do see the disgusting human puppet hori flay around) But that's it.
So Nine...
Im not one of those people who think a new character needs to be related to a pre stabelished one. Nine doesn't need to be a Todoroki, Shimura or hell even a lost Midoriya (hahahahahahaha as if hori would care for this family)
But ....imagine if Nine was related to Oboro, somehow, wouldn't that be interesting?
Maybe, maybe not.
Oboro's character became a thing to turns Aizawa into a better character...and fails. Kuro was sacrificed for nothing.
The thing about Shigaraki/Tenko backstory is that it feels... a bit overdramatic?
Well we can say that about his whole character, but the part of his backstory in particular when he kills his family is so exagerated for the sake of shock value that it kinda feels comical.
Horikoshi tried a bit too hard on make MVA feel like the edgier and "different" arc of the series, but the contrast in so big that I can't take it seriously.
Especially when Hori already nailed a dark tone without being super explicit or over the top.
Take the simplicity of Eri's backstory for example:
No blood, no unnecessary violence, just two panels giving a basic idea of what happened to Eri's father and yet the image of those clothes lying on the floor is much more haunting and eerie than the enterity of Shigaraki backstory.
Why Horikoshi stop being subtle with his storytelling?
...
Anyway going back to Nine real name, or the lack of one, I think it's interesting how that aspect of his character adds to the underlying theme of how AFO and Garaki dehumanize people, especially the ones that are part of their experiments.
We know very well how AFO doesn't view other human being as persons but rather objects that belong to him. This starts with his very own twin brother, which name Yoichi means something like "my first possesion".
And just like Nine, number 6 from Vigilantes was a child which whole life was modeled by AFO. They both are just numbers without a real name.
In this case the idea is presented even more explicitly because Six was a child who suffered some kind of amnesia and couldn't even view himself as a normal human with a face.
He even died as a monster without ever know if he had an identity outside being the number 6.
It's funny how you mention the idea of Nine and Shirakumo being connected somehow, as isn't the first time I've hear that.
It's interesting notice how they share this common theme about sky and clouds as part of who they are (Nine's name also is supposedly a reference to the term "cloud nine") both Nine and Oboro are individuals willing to sacrifice their own lifes for others, and ironically both of them ended being experimented by Dr Garaki.
I even have the headcanon of Kurogiri being the "Number 7" in this line of experiments were Nine and Six belong, as sort of missing link between Six and the sentient nomus.
I probably should make a post later explaining better this idea.
And yes for Horikoshi, Shirakumo was just a diposable character to make Aizawa look cooler and more edgy.
While the author of Vigilantes clearly invested a lot of effort on making Oboro a real and memorable character which complements Aizawa rather than just being an accesory. But that topic deserves it's own post as well.
P.S: I have an idea of what real name we could give to Nine, but I keep it for me at least for the moment.