From what I understood, when they hurt the teacher something possessed her, I don't remember the name of what possessed her. But if you look at the end you take a picture of a snake skeleton, it was what the 3 sisters were protecting.

and.. the other guy gets locked in a bathroom at school, you see it in a cinematic

引用自 𝑉𝑇𝐸𝑋：

From what I understood, when they hurt the teacher something possessed her, I don't remember the name of what possessed her. But if you look at the end you take a picture of a snake skeleton, it was what the 3 sisters were protecting.

and.. the other guy gets locked in a bathroom at school, you see it in a cinematic

Not protecting it, but rather locking it up.

the stone carvings at the end pretty much sum it up the sisters locked the Blorong up to stop the oroborous (the snake that bites its own tail representing an endless cycle) they tried to interrupt the cicle so there wont be a new blorong, while the guardian became weaker and weaker. Siska used her powers (you learn more about how she got them in dreadout 2) to start a new cycle and takes the newborn blorong to use it for her own agenda. (which you also learn more about in Dreadout 2)

The 3 Sisters needed new "Keepers of the Dark" because they lost most of their power so Linda and Ira became the new guardians with Ira being in the Dread and Linda in the world we know of. to stop the dread merging with the real world

yayans story (the dude in the bathroom) is continued in the manga / comic you get for free in dreadout 1 and 2 but iam not sure in which one of those 2 xD