Harry Potter (movie)

Once again Cerberus is not exactly hogging the lime light. He only appears a couple of times and he does not do too much. He is shown with three heads, a cranky attitude, and lots of drool. Harry, Ron, and Hermione find fluffy one night when trying to hide from Filch so as not to get in trouble for being out of bed. When they found fluffy they had just rushed into the room because it was the closest room to them. They find themselves looking at a dog that has three heads, and the dog is so large that one of its head was plenty bigger than Harry, Ron, or Hermione. When they first see the dog it is just waking up due to the disturbance caused by them rushing into the room. Each head waking up at its own pace and all of them responding in the same way. One just opens its eyes slightly to see the heroes while the middle one yawns and the one Fluffy’s right instantly pops up in alertness looking at the heroes. Not even seconds later all three heads realize what is in front of them and they get up, taking up just about all of the space on their side of the room. Saying that they responded as a grumpy hound is an understatement since it tried pursuing them even when they were out of the room. But, somehow the three kids were able to close the door that was being held open by one of the cranky, biting heads. Also, unlike the book version, Neville was not with the three who had burst into the room and met Cerberus. According to the Harry Potter wiki, they tried to make Fluffy appear more realistic by making his heads move independently and each head was given their own personality the three being smart, alert, and sleepy.

-Fluffy just after being woken up and seeing the bite-sized heroes in front of him.