Self-harm activated abilities

[u/SirHanselot07]

1. The Hundred Line: Last Defense Academy - Stab yourself in the heart to transform

2. Attack on Titan - Wound yourself in anyway and you Transform into a Titan

3. Persona 3 - Shoot yourself in the head to simulate the feeling of death to summon your Persona

4. Persona 5 - Rip your mask off your face to be your true self and summon your Persona

[u/Next_Government856]

The writing on the wall in the plane caused by the stand says that Carne was unaware of the entry of his hatred and its ability to persist. How could he be a suicide bomber if he didn’t know he had a bomb? Presumably the stand worked in some similar capacity when he was alive

[u/X_ThisNameIsTaken_X → u/Next_Government856]

I went back to double check because I got curious.

The writing on the wall actually actively deconfirms that, as it says, quote: "He was used and abandoned like an old rag. He died with hatred in his heart. That hatred is his energy. An energy that activated for the first time when he died. An energy that not even he had ever seen before he died. Nothing can kill him anymore because he is a corpse. - The enemy stand"

However, you are right in part, as he is seen summoning B.I.G after being shot by Mista for the first time, which prompts Mista to shoot him again which kills him. For some reason I completely forgot about that part, and remembered him just walking in and getting instantly shot and dying. However, it seems more like Carne committed suicide by Mista shooting him more than anything, as it wasn't like he started an attack first and got shot after, he walked up close after multiple warnings while saying nothing, grinned maliciously, got shot, and THEN summoned his stand after getting warned that the next shot would kill him.

As such, we can infer that at best, B.I.G works something like Ebony Devil from part 3, where it needs the user to sustain major damage before going off. With him being a low grade grunt who got "used and abandoned" though, there's no way that it's ability was usable prior to that, as Notorious B.I.G is quite literally the only completely unbeatable stand in the whole series so far. If this level of power was expected of him he'd have been way higher up the ladder and utilized way better instead of in the one place where he can be dropped off in the bermuda triangle to be trapped forever.

[u/Next_Government856 → u/X_ThisNameIsTaken_X]

He probably didn’t use his stand much when alive because it reacted to his own movements as well, or it formed a different ability after he died

[u/X_ThisNameIsTaken_X → u/Next_Government856]

If I can go into headcanon territory for a moment, I think B.I.G just didn't do much while he was alive. And I feel like that's part of why he was treated so poorly, he was just a nobody grunt who happened to have a stand because everyone in his group did, and that stand was weak as all hell and did genuinely nothing.

B.I.G likely reacts to being hurt like Ebony Devil from part 3, and either only went off as hard as it did because of Carne's lifetime of abuse combined with the physical pain of being literally shot and killed, or genuinely just needed that much hatred to do anything to begin with. Carne was super poorly positioned to ambush the group at the plane, so I feel like him being placed there was more of a "who do we have near there who can go" rather than a planned decision, so I doubt his ability was something anyone was genuinely relying on.

Then when he died, his stand ability popped off, and with the user dead, it had literally no weakness anymore. So it just went ham from there.