Gwen is a soulbond like Joy and Ulla, in her original books she is a subspecies of genetically engineered humans. It took a lineage of crazy scientist geniuses over a hundred years to meld the generics of a handful of bird species, and a human genetic anomaly: Polymelia, through many generations of evolution. Her wings are as quiet as an owl, and large enough for her to soar without effort like an eagle. They do not use breast muscles, the wing muscles are contained in the mid part of the body cavity sharing space with the lungs which are half the size of human lungs but are twice as efficient so you can't see anything unusual by looking at her abdomen. They attach mid-back and have a second set of shoulder blades, they have muscles external as well at the joints. If you feel up from the base of each wing you can discern shoulders, normal feeling upper arms with bi and triceps, elbow and normal feeling forearm and that ends with indiscernible wrist and fingers incorporated into the wings something like a cross between a bird and a bat in skeletal structure but with far shorter "fingers". This extra manipulation allows them finer wing control. Her bones are very lightweight, not just hollow, they're cartilage and they can bend 90 degrees without breaking. So a crash landing is nothing but a sore body rather than a broken body. Bone marrow is an issue though as the only traditional bones are in her wings so if you cut off her wings she'll become anemic and eventually die. Even her skull can be dented and pop back out. Her race is also naturally resistant to concussions, the brain is cushioned with a gel-like substance in the thicker than normal meninges.

Her wings also fold like you can fold your arms only behind her in the small of her back so she could somewhat hide them under a heavy coat if you're not looking for them.

The wingspan of her wings is roughly her height on each side owing mostly to her up to 3' long flight feathers. If one is lost they will regrow. If one is cut or damaged they don't so it is a very painful process to remove a damaged feather by pulling them out. If removed, a feather will regrow to 80% in 30 days and 100% in a season.

Her hair is also slightly feather like and very light so if she had long hair it would be a real mess. She has white feathers and even her skin is covered in micro-feathers instead of micro-hair which makes her naturally water resistant and she looks chalk white but if you get her wet like if she gets sweaty or cries, you be able to see her pink-ish skin underneath.