What exactly did it want?

I posted an answer to your same question, on the Paranormal Activity 3 board.



I'd say this cloud is Cumulo Nimbus.
Didn't he discover America?
Penfold, shush.

The whole thing was a lot scarier before the sequels started piling on backstory and motives.

https://www.youtube.com/watch?v=Z55W6ihUY-c
Moderators are terrorists.

I think it wanted the first born son of the family.

Basically, Toby wanted all first born males marked in the womb, from pregnant females born or raised in the Coven, have them undergo a virgin sacrifice ritual at age 6, then at 17 undergo a final ritual and be the vessels of Toby.

So, everything from Kristi being 'married' to Toby, brainwashing and memories wiped, haunted and eventually possessed and have the one that successfully becomes controlled by Toby, kills the family and abducts the first born son 'Hunter' to lose him to adoption or purposely plants him in the random family to give him a 'normal' childhood before moving near them and introducing Toby to 'Hunter' via Robbie a brainwashed first born from the Coven, the possessed Katie is still possessed or brain washed into teaching Robbie the ways of the Coven and his destiny, have him undergo first ritual by sacrificing virgin sister, then at 17 take control of him and have him undergo final ritual and become apart of the slowly growing demonic army of Toby, it was all about creating soldiers for him, soldiers that would fight for him in the coming Demonic War that would soon follow.

That's what I gathered anyway.

Possession in first stages has no effect as seen with Katie, but once 'bitten' or lost full control of their body, they are no more, just a empty shell.

Well, Kristi managed to escape the possession but it simply backfired on them and Toby just used her sister to put the plan in motion.

What I understand about this movie is that Toby wants the first born male child. In the 1930's a woman (I suspect grandma from Katie and Kristi in pa3) made a pact with the devil aka Toby for wealth and power. As we know Kristi was pregnant from her babyboy Hunter, first born male child in the family, he's seen as payment of the pact/deal.