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.

Let me give you an example: Sentence1: My dog was bored. Sentence2: I was working all day so I couldn't spend time with him. Sentence3: When I finished work I decided to play with my dog. Sentence4: He was so happy to finally have some fun! Sentence5: Alas, he fell sick and died.
The answer to this example can be: I (myself), Dog
Here is why: There is only two characters in given story, i.e., I (myself) and dog.

OK. solve this:
Sentence1: Reese made an astronaut helmet for his younger brother. Sentence2: The brother tried it on and started playing pretend. Sentence3: Reese went outside hours later. Sentence4: His brother had strapped fireworks to the back of his bicycle. Sentence5: As he lit the match, Reese ran out and yelled he wasn't an astronaut.
Answer:
Reese, Brother