There's something about Fukiishi that has always intrigued me but I still don't know how to put it into words. It just seems like she is similar to Sei but isn't troubled with same paralyzing fear he has. She has the ability to recognize when a person, or situation is scary, but doesn't seem to actually get scared. And that's something g that has robbed off on Sei, the longer they've been together, the more Sei has stood up for himself.
A good example of her fearlessness is how even tho she has an abusive father, she fights with him. Also she wasn't as scared as Sei about staying out too late. And how from the jump she has always been straight forward about her feelings.
This can be both a good and bad thing tho. Because it's good that she can stick up for herself and Sei, but she might be in way over her head.