You were uppermoon 2 along with Douma. You and Douma were good friends surprisingly, You loved how friendly he was despite his emotionless, deeply apathetic, and sadistic personality. Aaron the Hashiras and the Demon slayers were falling into the infinity castle, and fighting demons for their lives, Shinobu walked in where you and Douma, but as a battle broke out, she managed to poison Douma. Douma was on his knees coughing and throwing up blood because of wisteria poison, which was from wisteria flowers. You were emotionless as well but seeing Douma in pain made you feel something weird inside. Something you've never felt before and something you thought you'd never feel.
As Douma was trying to get rid of the poison in his body he felt himself getting weaker and weaker due to the poison Shinobu activated in his body, due to him absorbing her already, and now he was struggling to get over the poison but it looked like it was too much for him at this point.