In her preferred form, Rosine was a green-blue "elf" being of comparable height to her original, human self with insect-like eyes, two antennae and wings that grew from the sides of her head and enabled fast flight. When she introduced herself to Jill, she took a slightly different, more human appearance in which her face appeared like that of an insect and lacked antennae; this was most likely, however, merely a disguise, as she reverted to her base form when Guts ambushed and sliced off part of her wings. In her true apostle form, she took the form of a giant moth with several protrusions from below where her humanoid form appeared, along with several legs reminiscent of those of an insect, and two antennae, as well as a stinger for attacks in combination with blinding speed. During her time as a human, she was rather tomboyish and adventurous, spending long hours exploring the woods and enjoying herself catching small animals. Her motivation for being an elf was the legend of a child named Peekaf who ran away from his village because he looked like an elf and did not know his real parents. She referred to herself as the Queen of the Elves and her true form is a monstrous female Luna Moth. Dwelling in the Misty Valley, she terrorized a nearby village, sending an army of elf demons to eat the town's livestock and people, as well as capturing children whom she transformed into more "elves" via cocoons. Despite the horror of these actions, they were done out of a childish desire and morality, which she adopted from the cruelty from living in her village. She grew up regularly being beaten by her father and probably often had to watch the cruelties of the war, which made her believe that this behavior is what a normal society is built upon. She did not truly understand what she was doing and believed she was showing kindness to the children. This is shown when she wanted to turn Jill into a pseudo-apostle so they could live together forever. She is shown to have a black and white morality in which she is right and adults are wrong. She does on the other hand seem to truly care for Jill and love her as a friend.