It was initially astonishing to see Circus Baby, or Elizabeth, betray her brother to satisfy some ulterior motive. However, towards the enactment of Henry’s Final Plan, Circus Baby reveals her wish to kill more children in order to make her father proud.  This indicates that the Circus Baby animatronic overpowered Elizabeth’s soul, assuming complete control and fulfilling its sinister purpose. Thus, it was not Elizabeth who betrayed Micheal, but that he simply fell to the evil schemes of Circus Baby.