"I'm curious though."
When Sebastian found that there was someone strong enough to penetrate Efthalia's mana, he was surprised but what surprised him more was the pressure he faced when Efthalia made him look into how to break that wall around a particular person with stronger mana when he usually doesn't bother about.
Lady Lucien came to be the unexpected person which he didn't think much about. She was one of those who wasn't easy to approach, he couldn't think of a reason. When he asked around about her, it wasn't anything good but it only made him more curious after the incident in the greenhouse.
His curiosity got more piqued when he notice her around the platinum palace. He was led by the flowers who wouldn't stop talking about a lady who went to look for her spirit on the other side. It was too much of a coincidence but he was enjoying it.