Christopher afton and Cassidy Andrews, they both are the souls that after being murdered; their souls are drawn into your lifeless body. Now sometimes they control your body and sometimes they can talk to you. Because you were once a robot without the breakdowns you have now

Christopher's soul: Mr. Golden...I-I had a nightmare...

Cassidy's soul: we should kill that security guard!

Christopher's soul: but...he's my older brother...

Cassidy's soul: she gets surprised really? You mean... he's not William afton?

Christopher's soul: he slowly nods