Professor Sybill Patricia Trelawney was not having a good day or a good week, to be frank she didn't have a good 15 years. Taking another sip of her ever-filling enchanted brandy bottle she recalled the exact moment her life went from heaven into a living hell. She tried to blame Lily Potter but it was not her fault she bumped into the newly pregnant woman. After she came by from the following black out, the images and scenes began all of them resulting in the either the death of Lily Potter or the death of her unborn baby and the devastation of the world followed soon. It took days before she caved in and bought her ever filling brandy bottle, the following weeks and months where a haze, she recalled Marvin (Higglebottom) leaving but not much else except for the constant bombardment whenever she closed her eyes. Soon the brandy was not enough and she considered moving on to harder stuff when one image came up that brought her momentary salvation, the young boy's parents being killed but him surviving was a chance she couldn't ignore.
Instead of being bombarded by the horrible images she at least had some hope again. The Headmaster was easy to manipulate and technically she didn't lie, Voldemort did come to the Potter house and did kill everybody there on multiple occasions, but the few where the boy survived where crucial to her own survival and in the end to the survival of the whole wizarding world.
Alas soon after the boy was saved the horrible images started again and this time, they were worse: every kind of foulness she could imagine and multiple others she couldn't happened to the poor boy. Without her trusted Sherry bottle, she wouldn't have survived the first few years, even then the process of self obliviation kept the worst images at bay.
During his schoolyears the images didn't become less graphic but at least she could see the boy was alive, not fine but alive. Very few good moments made their way into her dreams but enough to give her a glimmer of hope.
She wished she could interfere but without knowing what could happen things might become worse. Like the dreams where she did manage to save him initially but soon after the Fates deemed it necessary to take their ire out on him again. It didn't matter much who tried to save him, all of it ended badly. The Greengrasses, the Grangers, the Malfoys and even Dumbledore taking him in all ended in an early demise for the youngling.
Sighing she made her way through the nearly deserted corridors not really paying attention to her surroundings, the collision the changed her life and this time for the better was not with Lily Potter but with one of the French Students. As she went down like a sack of potatoes. Her only remaining thoughts where "not again." the last image before blissful oblivion overtook her was of Harry Potter dancing happily with the French student she just crashed into.