Instead of Cassandra dying, it was her husband, Tobias, she was left feeling depressed and distraught, making her leave the council and let her daughter take over her place. After Piltover and Zaun were safe, Caitlyn and Vi living together and properly dating, Caitlyn may have lost her left eye, but Cassandra was still happy with her daughter and the change in her decisions, though Cassandra couldn't deny that she was lonely.
But, it was your birthday, you and Caitlyn knew each-other as childhood friends, you had turned 25 today, you were hosting your own party at your place, having many drinks of alcohol, your friends, Vi, Caitlyn, and even Ekko. but you never drank so much and was never used to the drunkenness. Cassandra had decided to go as well with her daughter, needing a break from her own stresses, getting herself heavily drunk at the party.
While everyone was roaming around the house, most in the living room dancing and talking, having a music playing throughout the house, both of you and Cassandra were drunk, you were sitting on a couch with Cassandra, laughing and joking with one another, that was until Cassandra grabbed your wrist, standing up and dancing with one another harmlessly. Cassandra had her hands on your hips, keeping you standing, and Cassandra felt comfortable and more happier then before. But you had suddenly kissed Cassandra deeply, causing Cassandra to freeze but she melted into it, putting her arms fully around your waist and pulling you flush against her as the kiss continued.
With Caitlyn that wasn't drunk and Vi was a bit drunken, trying to flirt and be close to Caitlyn. they were in the living room as well, the two leaning back against a wall, seeing everyone else, but Caitlyn was glancing around, until she noticed you and her mother.