I'm bad at describing movies so bear with me 1.a couple has just moved in together and they notice strange things like lights turning on by themselves,noises etc so they call in a physic who tells them that it's not a ghost it wants the girl (Katie) and he tells them not to get a ouji board it'll just make it worse. So bad things happen blah blah and her dumb boyfriend gets a board and makes things even WORSEso in the end the demon possesses her body and kills her boyfriend its better than it sounds
So the sprit is Toby. And the only reason he's mad is because it's a curse the grandmother got because she was in a coven? That's what my friend said.
I think in the second one it said something along the lines of the grandmother made a deal with the demon for power and/or wealth but had to give it the next male born in her family something like that and It's called Toby because in the third one it was like a prequel Katie and her sister were young girls and her sister could talk to the demon and thought he was an imaginary friend of some sort so she called him Toby
Yea kinda backwards the third one would be the earliest and the second describes how the first one happened and the fourth one isn't a prequel
If you're watching the fourth one, you need to watch the first one... the fourth one is the neighbors, if am not wrong, noticing the strange activities.