Paco once lived alongside Ferdinand, Nina and her father on their farm. They engaged in bonding activities like watching television together at night. His jobs, stereotypical to that of a sheepdog, included herding the chickens on the farm.
Like most Collies, Paco has long, shaggy white and black fur. However, his markings are much more distinct than other dogs of the same breed as his ears and eye rings are very prominently black, while the rest of his body, a clean shade of white. He has a very round large black nose and eyes. Paco also has messy locks of fur on his head, some draping over his forehead.
Paco appears to be a rather conformist and stubborn dog, believing in the "laws of Nature" and having a strict adherence to regulations and norms. This can be displayed when he curtly told Ferdinand that they had to fit into the expectations of their kind and told him that they could not be "brothers", despite him secret desire to be his brother. And he is also known as protective, assertive, cranky, organized, persistent, affectionate, clever and observant.
After Ferdinand falls out of a train while escaping Casa del Toro, Paco finds him down a muddy hill and alerts Juan so that they could save him. after that Paco and Ferdinand grew up together. Paco tries to act like he does't care much for Ferdinand but this is shown to be nothing more then an act, as his tail wags (a sign of happiness in dogs) whenever Ferdinand calls him brother. Paco also seems to be protective of Ferdinand at times such as when Ferdinand accidentally destroyed the village. When animal control came to capture Ferdinand, Paco told the bull to run and hid and tried to divert their attention away from him but this did't work. When Ferdinand is driven back to Casa del Toro Paco, along with Nina and Juan, sadly watch as Ferdinand is taken away. When news of Ferdinand's upcoming fight with El Primero makes its way to the farm, Paco alerts Juan so he and Nina can go and retrieve Ferdinand.