Given the task definition and input, reply with output. 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.

Sentence1: Sammy was a very determined baby. Sentence2: She was curious and always wanted to play. Sentence3: One day she wanted to chase after her older sister but couldn't. Sentence4: She decided to take her first step and go after Sister. Sentence5: She started and she couldn't stop!
Sammy, Sister