Phantasm: Thinking about Ghost Puppet laughing at the Shie Hassaikai and having Thoughts.
Imagine spending 200 years being stolen and used for the worst things imaginable back to back to back. Your wielders see the news and maybe you don't get it cause you're not even sentient, or maybe you do, but nothing they say about you or your wielders are good.
Then after 13 wielders, you've had enough. You slip right out and attach yourself to the first person you can and that's it.
The first decision you'll make in 200 years. And huh, no quirk, and Uh Oh, it's a child, a fucking middle schooler. And the kid panics until it hits that he can't be a hero. All he thinks is that he'll go to turbo super jail and shuts down.
And shit you just got a grip on sapience with like, 1 pinkie and honestly not even, so you kinda have to agree with the kid, 13 villainous wielders isn't a good track record. So you just kinda watch as the kid, who knows just about everything about you that's neat, just kinda flows around with no real energy and you think you're feeling guilt wow that's a sucky emotion.
And then the kid goes vigilante.
It's not on purpose, the kid just sees a mugging and hey there's a conveniently magnetic trash can lid right there next to the mugger and now it's conveniently and rapidly relocated to the side of said muggers head.
And the kid is happy, you can kinda tell by the big smile on his face, but the tears are confusing so you don't really feel what you're feeling just that something is there.
And the kid keeps going, unsteady and with more close calls than you're comfortable with (and Hey! Discomfort is an emotion! It Sucks!) but he makes it out every time, and he's feeling a little better. (You're also feeling something separate from the Discomfort, not sure what.)
He's analyzing all the quirks you've collected and he is going nuts, using them in new, insane ways and every time you think he's capped out what he can do with a quirk, he's found some new combo, or mechanic and it's even crazier and the kid is ecstatic every break through. (Why didn't anyone else figure this out? Why didn't the previous wie- users wield you like Midoriya? He's not even out of Middle school!)
Then, after many nights of vigilantism, he runs into an even smaller kid. And at this point even you can tell something is not right, even before she begs you to not let that weirdo in a bird mask take her. One rapid information dig is all it takes figure out the Shie Hassaikai are going down.
(Anger comes in many flavors you've found. Anger at injustice is the most bitter.) (It's become the most familiar throughout your memories.)
And it's in the middle of the fight with the Hassaikai that you figured it out. As you're slugging it out, as Midoriya is not quite dancing around his opponents, as he puts his all into saving Eri from these monsters, you finally get what you've been feeling.
You're happy, not just from fighting. You fought for your users before, and every memory about those fights are at best indifference and at worst disgust. Just fighting isn't what makes you happy.
It's fighting to save another, for no other reason than they need saving, and you have the ability to save them. And you're furious too that it took this long for a good man to not use you, but actually wield you, let alone for good. And you're grief stricken that it's not a man, but a child. And shameful that it's your fault he wields you. But through all that you're happy. You're so happy you could just start
(In the middle of the fight, as Rappa and Ghost Puppet are fighting, the Ghost Puppet opens its mouth and, for the first time in 200 years it’s heard)
(It laughs and laughs as the fighting slows, everyone distracted by the laughter, a few glances to Phantasm show that even they're frozen at Ghost Puppet's laughter. But not for long.)
(The fight resumes, but now with an eerie laugh track, as even when Rappa throws the Puppet through no less than three walls, it doesn't stop laughing. It's only as Izuku makes his way to Eri's room that Ghost Puppet's laughter peters off.)
As Izuku reaches Eri's, and as Ghost Puppet quiets, he throws a look to it. Its empty sockets stare back.
Izuku takes a moment, two, before turning back to the door to Eri as Ghost Puppet retreats back into him. The time for quirk analysis is later. Eri comes first.
(I have no idea where all that came from, this supposed to be like one paragraph talking about how Ghost Puppet would evolve and then a second paragraph that was the bit about GP laughing I typed out on my phone at work and then it exploded. Clearly Ghost Puppet possessed me to write about it.)
(Also I'm not even sure if this counts as just ask, this might qualify as a AU fic, even though it might not fit with your idea of GP's character.)
(Also sorry if there’s formatting stuff I had to take screenshots to save and copy/paste into a note to save it from tumblr’s ask box.)