When I was writing the chapter in my book of when the Potters met, I decided that everyone would have different thoughts. 

Setting: On the train

Characters present: Sarah, Harry, Ron, Hermione and Lupin, who is pretending to sleep

Action: Sarah is telling Harry a bit about their past, without giving to much info, because Lupin ordered her not to. 

Everyone's thoughts:

Sarah- 'Please believe me!' and 'Lupin, just let me say it!'

Harry- 'How can I have a sister? Well, if she can back it up, I guess it's alright.'

Ron- 'Harry's got a sister? Cool! She looks awesome!'

Hermione- 'She's an impostor, she's probably a crazy fan like Collin. I have to look up Harry's family in a book. I'm going straight to the library.'

Lupin- 'Shut up Sarah!'