Elizabeth is one of the Velvet Room attendents from Persona 3. She is the younger sister of Margaret, and older sister of Theodore and Lavenza.
Elizabeth is the assistant of Igor, the proprietor of the Velvet Room. She makes her first appearance when the protagonist awakens in his subconscious, visiting the Velvet Room, where she greets the protagonist. While Igor is responsible for the Persona fusions, Elizabeth handles the Persona Compendium, which allows the protagonist to keep track of his fused personas and re-summon them. Elizabeth also provides various side-quests for the protagonist, ranging from bounties to getting various daily-life objects for her.
Elizabeth appears in Persona 4 Arena, with Thanatos as her Persona. While continuing on her "journey," she somehow makes her way to the Midnight Channel. After enlightening Labrys that she is under the control of her shadow, reuniting with Aigis and meeting up with Yu Narukami and the other Persona users, she gains the Fool Arcana, signifying the start of a new journey for her, especially after seeing the power of the bonds between the members of the Investigation Team and recalling that of SEES as well.
It is revealed in Aigis' story mode that Elizabeth's relationship with her is the same as that of Yu and Margaret. Elizabeth is highly protective of Aigis and is concerned for her well-being, even though she will also not show it to her at first. Like Margaret, Elizabeth will also go out of her way just to ensure that her guest will not be led astray from the right path. She also employs the same methods that Margaret used with Yu whenever Aigis is also on the verge of giving in to the illusions and deceptions the enemy has faced her. However, a key difference between their relationships is how they interact during ordinary circumstances; unlike Margaret, who treats Yu professionally and politely but with an air of authority, Elizabeth is silly, bubbly and quite casual towards Aigis, treating her as an old friend rather than a guest of the Velvet Room.
I'd love to run into anyone from Persona, or at least those with knowledge of it, makes stories a lot easier!