she has four human souls, although she cant feel out of three-and-a-half backstory: a day with the ninja after the flood. normally, they would all poke fun at each other, but today, they had to be careful. they had to traverse through the field of the fallen. the souls of fallen humans and monsters disappear and are sent there to live inside of glowing capsules hanging off the trees. if you touch a capsule, the soul will turn into your soul type and you'll absorb it aura and kai had gotten into an argument again and kai pusher her into a tree. the impact knocked three capsules off, which she absorbed. the others got angry at kai, but aura felt everything x4. furious with kai, her souls' power consumed her, turning her into a terrible beast. she severely injured kai, when finally she turned back into her normal form. she was so guilty she didn't stop apologizing until kai told her to stop. scared at the beast she'd become, aura put one of her souls into a charm on her locket. months later, she had a mental breakdown, so cole (one of the other ninja) gave her his mother's locket. three weeks later, she put another soul into it. then she got her hand cut off, and put one and a half into her robotic hand. she cannot feel out of any of those souls, and only has half of a soul inside of her, but she still feels more emotions than any normal person.
the soul is made up. it is the (emotional) pain soul. the power turns you into a giant, horrifying beast go inside to see the beast part, it's really creepy though i'd say 13+