When Jackson and Serenity were dating, they didn't use any birth control, but because of her injured uterus, it was practically impossible for her to get pregnant anyway, so it was not a problem she had to worry about. In a way, she was lucky.
At least Jackson and her didn't share any children, so they could make a clean break!
However, deep down inside, she felt a tinge of regret.
If she had a child, that would mean she had a family member connected to her by blood.
Without a child, she was