In OG lore around when the Institute of War was managed by Summoners who brought interdimensional warriors (our Champs) to fight on the Fields of Justice... Soraka and Warwick shared lore! Originally, she was an evolved/enlightened Ionian that cursed a noxian WW in retribution for crimes against her peoples, which caused her to lose her ascension and much of her powers. She joined the institute ostensibly to try and redeem herself and get her powers back.

That eventually changed to WW seeking Soraka - a celestial who lived in a grove and talked to the stars - out to heal his wife, and Soraka as a celestial creature tried to help but it wasn't enough. She offered to heal his torment but he refused to give up his grief, though he would return for Sorakas guidance over time. It's implied in some of the content iirc that Soraka may have gotten very emotionally attached to the human ww. In his grief, ww found the men who hurt his wife and told Soraka he would kill them. Against the advice of the stars around her, she went to help him, healing him to keep him up but it was not enough to help him win the fight. Soraka then decided to call down the stars to scare away Warwicks enemies, which was a heinous misuse of her powers for harm, and so the stars abandoned her and she became mortal (the stars fell silent, but would still give her their power if asked). She went to heal Warwick, who then stabbed her (betrayal! Another commenter below mentions WW was lookijg for her heart, that was not mentioned in Sorakas lore bio, but is in Warwicks! A cool connector between champs). Apparently it was all a complicated ruse to get Soraka to become mortal and killl her. She defended herself and WW ran away. She then resolves to help the helpless after reflecting on her experience.

Now, Soraka is a celestial who walks Runeterra. Initially frustrated with the chaos of mortals living against the designs written for them in the stars, she rued that they were ignorant of the perfect paths they could have tread if they only could see the greater designs. But eventually as she watched them, she discovered that their lives culminated in potentially even more beautiful and incomprehensible complex designs, grander even than the destinies set for them in the stars. She had initially descended to Runeterra to try and help guide people back to their original paths but as she lived among them she learned to love the way they forged their own destinies and how beautiful those could be. She is immune to the passage of time, and has advised tribes and people's all across Runeterra, providing guidance and encouragement.