Just like Lust, Gluttony can't clearly recall her previous hosts. She knows there have been dozens of companions in her long life due to the knowledge in her mind.
But there's only knowledge there, no real memories.
Yet, she can sift through that knowledge just like the other Sins, and that's what she's doing right now as she watches Lucien and Naomi kissing.
Gluttony is desperately trying to find something in her memory that tasted better than the flavor she's experiencing on her lips now.
She doesn't want to admit the obvious, but no matter how hard she tries to remember something better, nothing surpasses the taste of Lucien's kiss, not yet.
And just like Naomi, she becomes more addicted to it with each passing second, which leaves the little demon both excited and frustrated.
Another thing Gluttony shares with the other Sins is a natural disdain for Lust, after all, her powers and methods always seemed weak compared to her sisters.
Sorry for not posting for so long; I got really sick, and I'm still recovering. I didn't manage to stock up on new chapters due to my health, so I can't promise daily chapters yet.