Clarification: both endings are canonical, you choose the ending you like the most or the one you feel more identified with.
Thanks for making it this far and ...HAPPY ALL SAINTS' DAY!
Lucy's succubus skin that is to say, Infernia during one year adapts, the problem is that Lucy on purpose was consumed by that skin to be only one, after one year, the skin can be taken out of the user and put it back with all the attributes that this skin has but without the painful process of assimilation, since these organically functional hyperrealistic skins work as the fingerprints of a person: they are unique and unrepeatable, and only work with the first user who puts them on another person would only be a mere empty shell, these skins only obey the unique mental commands of each person and that is why each skin is unrepeatable, usually this type of layer lasts about 25 years maximum (although it depends on the price and quality of the same), then it dissolves as it is biodegradable, in the final A, Lucy is still 因菲娜 but now using a fake skin of her human self, as I wrote, these skins do not prevent the person to do their daily activities and organic functions at all, as these when using them are fused at endodermal, ectodermal and mesodermal level.
In the ending B, Lucy is not wearing any skin, she is herself as she wants to present herself to Blaze without hiding and be honest with her.
In both endings, Blaze no longer has the succubus skin on, it dissolved as it is biodegradable, and she would not want to wear something like that again, but Lucy, in the A ending is still wearing the 因菲娜 skin and accepted it as her "real self" and is wearing a fake skin of her human self, but, with the caveat that she will never take Blaze down that path again as she does not want to lose her and will only show herself as Lucy when interacting with her.