Detailed Instructions: In this task, you're given a story (which contains five sentences only). Your task is to find all the characters which are available in the given story.
Q: Sentence1: Roy was a retired construction worker who lived alone. Sentence2: He had recently been widowed and was looking for some company. Sentence3: One day Roy's son and his grandchildren showed up with a surprise. Sentence4: The surprise was a new bulldog puppy! Sentence5: At first, Roy was nervous but he quickly fell in love with the dog.
A:
Roy, Bulldog puppy, Roy's grandchildren, Roy's son