Sirius Romanée-Conti Character is Mother Fortuna, possibly Emilia's stepmother.
When we look at the character's design, we see that she has silver hair and purple eyes. These two features are also the same in Mother Fortuna. When we look at Sirius Romanée-Conti's physique, we see the same physique in Mother Fortuna.
We can generate highly probable possibilities based not only on physical characteristics but also on the story. As you know or remember, Petelgeuse accidentally killed Emilia's stepmother. He probably regretted what he did and somehow managed to bring Emilia's stepmother back to life. But whatever way he did this, he lost his mind and went crazy. Also, the resurrected Emilia's stepmother was also reborn with a scratch memory, but due to the way she was resurrected, she too lost her mind and went crazy.
If you listen carefully to Sirius Romanée-Conti's words in Season 3, Episode 3, she tells Petelgeuse(Actually Subaru), you gave me my name, you took good care of me, etc. She says things like that. When do you give someone a name? Either she/he is a baby (newborn) or she/he is your slave.
We'll see in the future.
Fun fact: The two characters are the same height. There is no need to worry about these characters being exactly the same.
