Ransom

A few days after the banquet, which was spent without Clara and Leo having enough time for each other.

Leo was busy with his work, while Clara was practicing her elemental powers. She could control it, but was still trying to test the air element, because it's very dangerous.

She's doing this because of the people that's tailing her. She's not sure what they want and want to be ready.

It was Leo who stopped her before she could kill Jerry's men that kidnapped them the last time. She didn't want to make the same mistake, because she can't just kill humans.

If she killed a human, it must be when Leo's life was threatened and she had no choice. Even if it comes to that, it must be 'either Leo dies, or the other party does' situation.

So, there's no chance for that at all. She's trying to control it and be totally conscious about the surroundings to make sure the person suffers, yet lives.