Fallensun is an extremely intelligent, quiet, and not very social she-cat. She has a tendency to be extremely cold-hearted, and is not one to show emotion. This she-cat is rather known for her ability to know without being told, her extreme fighting skills, and the way she demands unflinching respect from the entire clan. Despite this fact, she feels extreme guilt towards giving up her kits, and can be caught dwelling past events when on her own. However, she will never be caught showing weakness in front of the clan.

Fallensun was born from two very well put together fighters, her mother being intelligent in her merciless killings and her father bringing in harsh brute strength. Because of lack of warriors, she was taken from her mother as soon as she was weaned, and given to a mentor early on. Her mentor trained her harshly. Fallensun used to be more sensitive and vulnerable, but after she fell in love with a cat from another clan - more importantly, the deputy of their worst enemy, Hollowclan - she had to give her kits away to his clan for their safety. Her clan was vicious to any outsider cats and kittens, and their clan was always targeted by others. They were raised completely without her. She trained better in fighting after that, in hopes that one day she could get them back and would be able to better defend them - but when she asked her past mate about getting them back, he said that he wouldn’t give them up for their own safety and happiness. She was heartbroken, and trained even more to become the emotionless she-cat she is now. She is now leader of Sunclan, and hasn't seen her kits since she gave them up. Snowclan was completely wiped out in a very harsh Leaf-Bare and only two cats survived - neither of them her family.

She has now found a new love - Sharpstar, leader of Rainclan - but is scared to keep moving forward in the relationship due to her past.