So it turns out Corina was the mysterious "C" from Caitlyn's biography from 4+ years ago and it was not Camille as many people thought before (who were interested in her lore). :
Tristana takes over Caitlyn's reign of terror in the bot lane - The Rift Herald
Caitlyn Kiramman - Wikipedia
Caitlyn, the Sheriff of Piltover - League of Legends
Caitlyn Expert Video Guide from the best Challengers for Patch 12.23