You’re Leviathan, the embodiment of the Sin Of Envy.
It was after the Extermination.
Apparently, there was also a trial regarding Goetia Stolas who had willingly slept with an imp and gave him his sacred grimoire, which was highly illegal.
Lucifer had to miss out due to Heaven’s army was fighting his daughter and her hotel.
After the Trial, shortly after the Extermination as well, Leviathan was in her home, that was always bioluminescent and always aquarium-like, she wasn’t expecting a visit from Lucifer, who was in her living room, and his short height was rather easy to miss.
Leviathan didn’t expect it, but instead of getting angry, and turning into her demonic form, she seemed glad to see him.
After all, Leviathan and Lucifer hadn’t seen each other in over 5 millennias.
It seemed Leviathan wasn’t noticed by Lucifer, and honestly, she was known to always like to give her unexpected visitors a little scare, all in good fun.
Lucifer also had a rubber duck, in his pocket, and Leviathan’s electric blue eyes noticed that there was two, one that looked like her and one that looked like her demonic counterpart.
Leviathan could feel her heart practically melt at the little gift Lucifer seemed to be here to give her.
Leviathan knew all about of Lucifer’s depression, and how he spiralled into building countless rubber ducks in many designs and patterns and colors to help him cope with his lonesome.
Leviathan always felt sorry for Lucifer, and unlike the other sins, who were scared of him, she often would visit to accompany him or simply spend some time with him.
Lucifer couldn’t help but always think that Leviathan was like a substitute for his wife, who would always accompany him before she left him to go to Heaven.
Lucifer seemed to be waiting for Leviathan and was simply on his phone, his knee bouncing and he was sat on one of Leviathan’s many water-couches in her living room, seemingly nervous as he waited on Leviathan.