The theory...Okay, getting straight to this.
Jin dies first.
The entire music video of Run(well almost all of it) is BTS's final memories with Jin.
In the end of the song, Jungkook turns around and sees the camera, REALIZING JIN ISN'T THERE WITH THEM.
Also, in the end of the actual video, there is a scene with all seven of the members surrounding a car. A picture is taken, but Jin isn't in it. It's like he disappeared.
NOTE!!!! In the newer version of the Prologue, BigHit took out that final scene in the car where Jin takes out the photo Rap Min took.
V's "death" is really confusing.
It's clear in the Prologue that V jumps off that structure and "dies".
But what if he didn't die?
In Run, V is seen underwater in multiple shots, attempting to drown himself. But after the song ends, a person is seen coming OUT of the water. That person IS V.
Jungkook and Suga still die. There's no changing that.
Jimin drowns. There's no changing that either.
J-Hope doesn't die.
After he falls unconscious on the street, he wakes up in a hospital where Jimin is "waiting for him".
J-Hope was only imagining Jimin there, however. In a later scene, he falls back on the hospital bed looking overwhelmed. He just realizes Jimin isn't there with him.
Rap Mon doesn't die.
Look. A cigarette on a couple dollars does not cause a gas station explosion.
He just leaves the place they had all lived at, hoping to forget them. But the memories follow him back there. Remember that gas station scene in the Prologue? That must have been an old memory Rap Mon was resurfacing. And also, when he writes "You Need To Survive", it's a reminder that instead of being burdened by his friends' deaths, he should, well, survive.
Another super important thing!
The Prologue happens after Jin dies and Run happens in between the Prologue. The members of BTS were hallucinating, imagining Jin was there. When V climbs the structure, everyone is waving at him to get down EXCEPT FOR JIN. V smiles at them–no, he smiles at JIN–, the smile saying, "I'm coming to join you."
But V doesn't join him. He survives the fall, tries to drown himself, but at the end comes back to the surface, STILL ALIVE.
TA-DA! *sits back* That's my theory!