Just curious why you dislike Fred. I find her an extremely grating, overly cutesy Mary Sue (loved by everyone, the most brilliant genius ever, gets praised and adored constantly, etc.), so you're not alone.
Yup - her character is also kind of flat - no arc there. She is sweet and good when she is rescued - she is sweet and good when she dies. She has no faults - I can’t imagine her having any inner darkness, even screaming at everyone and slamming a door.
She seems more like an icon for everyone to adore than a real person. A cinnamon roll, too good for this world. I also find her oddly sexless - no spark with either Gunn or Wesley and they both spark with others. I think it’s a combination of the writing and Amy Acker.
I do love her death scene - and there a few other scenes I like. But overall she annoys me now.