I Have to Save the Magical World to Live a Good Life

(The parents' generation + the children's generation + a coming-of-age arc + a Gryffindor heroine + no character bashing or breaking up canon couples. The male lead is Sirius Black. The early story focuses on personal growth, with romance taking center stage later.)

Ilandy Weil had been waiting for this day: the day her Hogwarts acceptance letter arrived.

She had only wanted to enjoy her wonderful school life, but when her best friend was about to meet a certain death, she began revealing bits of the future through prophetic dreams to prevent it.

Can she change everyone's fate this time?

(Note: The male lead has little presence early on. Most of the relationships in the story are familial or platonic, and the heroine is not a Mary Sue. The pacing is fairly quick. The butterfly effect leads to major changes later on. Some GGAD.)