How is Poppet the dreamer?

Poppet's full name is Penelope Aislin Murray, and she is the younger twin sister to Winston Aidan Murray, who is nicknamed Widget. Widget was born six minutes before midnight on October 13, and Poppet was born 7 minutes after midnight on October 14. Their births coincided with the opening night of The Night Circus. Their mother was a part of the magical circus, so the lives of the twins are intricately tied with the circus itself. This is why they are born with special abilities.
Poppet's ability is related to her being the dreamer of the twins. Her ability allows her to tell the future through the stars. Widget's ability is to read people's pasts. His ability is a backward-looking ability, but Poppet's tends to be much more forward looking and hopeful. She sees what could be and what will be. These things might be bad, but Poppet is a continually upbeat and lively character. Pair these characteristics with her ability, and it's apparent that calling her a "dreamer" is a good description.