How was the Welch family’s reaction to the rat different from other families in their home

From the text:

Brian threw the cast­iron skillet at the rat. It hit him and clanged on the floor, but instead of fleeing, the rat hissed at us, as if we were the intruders. We ran out of the kitchen, slammed the door, and stuffed rags in the gap beneath it.
That night Maureen, who was five, was too terrified to sleep. She kept on saying that the rat was coming to get her.