Damien didn't just tell Lilith about Joyce's dream, he also expressed his theory about how she might have started having those dreams in the first place.
"So, you gave that plant to her, huh?" Lilith asked as if she was dazed after listening to everything that her son had said until now.
"Yes, now that I think about it, I think I was destined to steal and bring that plant to Joyce. I don't think she would have recalled her past if it wasn't for that plant. And I don't think we would have ever found out about her reincarnation."
Damien recalled a certain incident from the ship and mumbled, "It looks like Ariel's grandparents don't reveal such information to us. So, I am glad that I took that rash decision during my childhood."