Why do you think the animatronics act the way they do?

I don't really think there's a backstory to the animatronics. The phone guys basically stated they're programmed to not let any exoskeletons not have a suit, which is why they stuff you inside. However, I do think the animatronics have human like feelings. But their feelings are programmed as well as their ways. However for Foxy...
Foxy is scarred from the bite of '87, which is why he hides in Pirate Cove. He fears that the other animatronics will beat him up if he leaves, as explained by his exoskeleton being shown in his legs that they have previously beat him up. But if you keep the camera on him too long, he thinks somebody is giving him respect again, and sprints to the security room only to find out it is and exoskeleton. Enraged, he does as all the other animatronics do, he kills the player.

Maby their lonley

yes they are haunted by the child victims of the Bite of 87.

they have dead children in the body

Because they kids inside them all act differently. Foxy could be the shy one who gets worried when you don't check on him.

Well there haunted my theory is that they come after you because they are angry with adults so they come after you and with foxys good thing maybe he wasn't murdered by an adult my theory is the kid died because he got a heart attack because of one of the animatronics scared him the same way he may accidentally kill you and the overs kill you by the way they got killed like when toy bonnie jumps on you maybe some one jumped on the kid and killed him

Well the "Purple Man" killed the children right?. The animations (the souls of the children) have the image of the man in their mind..which means When Mike is working at Freddy's pizzeria for the night shifts. The animatronics (souls..) are seeing Mike as the Purple man. So that causes them to try to kill you in the game.For revenge.. Because from what they see .. Your the purple man..Not literally but from their eyes they see you as the purple man. :I (might be confusing hard to explain) XD

Children's souls haunted the animatronics also remove Google plus remove twitter remove Facebook and remove DMCA and remove eula and remove nsa and remove the safe harbor worshippers and it's terrible acts and remove apple technology and remove Skype and remove Microsoft technology and remove netflix and remove DRM and remove Hulu and remove red box and remove the ndaa and remove all copyright acts and remove all the utility bills and insurance commercials and remove all the taxes and fees and remove mpaa and remove riaa and remove IRS and Remove Fbi and remove Sony and remove ACTA and remove COPPA and remove AOL and remove ACA and remove Verizon and remove AT&T and remove etrust and remove FOIA and remove adobe and remove Spotify and remove TPP and remove governments and remove congresses and remove FDA and remove DEA and remove ACLU and remove verisign and remove Kindle and remove nook and remove Mozilla Firefox and remove safari too and save the link from the FCC and remove TRUSTe and remove EME and remove PPACA and remove Obamacare and remove HIPAA and remove CETA and remove TIPP and remove TPP and remove TTIP and remove TISA and remove TTP and remove RTI and remove CALOPPA

It's because of the crying child,remember that Purple Guy
Stab the animatronics with the ax and then the crying childs
Came out of them.