Fear was indeed a powerful motivator, and it was one Helena knew personally. Like Anakin, she herself was afraid of the darkness she had within her. It was a constant struggle with herself to ensure she didn't fall, that she didn't let her guard down. That fear of one's self was something Helena related to in Anakin. She didn't know his entire story, but what she did know put them both in the same category. They both had much in common, and at least to Helena, it was reassuring to know that there was someone who knew what it felt like to be afraid, to hold a hate and anger so powerful that they were pushed to commit atrocities.
At least when Anakin acknowledged he did want children, that was a good thing. It would make approaching the topic easier. And it did show Helena that there was a desire for Anakin to fight against the darkness within him. The wanting of a family could never come out of a dark place. That kind of love and desire was typically a pure one, and one that could motivate someone to stay on the right path in life. She just needed to find a way to work through the fear that Anakin felt to get him to understand that. Because she did believe things didn't have to be the same here. No doubt things were all ready different than what Anakin's path would have been in his own world.
After all, sometimes there were multiple factors in someone following a darker path. While Helena herself had experienced one singular event that made her snap, everything had snowballed afterwards that had led to her ultimately losing her mind and trying to destroy the world. But there was undoubtedly a lack of some factors in this world that had added to Anakin's downfall in his own. Though it could just be Helena's innate belief in the good in people that made her think that, but it was rather difficult to tell that right now.