Rollo was "hostile", but Rachel was able to earn his trust over time by giving him scraps of food she saved from her lunch. He grew increasingly agitated and unhappy kept chained up for most of the day, until Rachel couldn't play with him without him hurting her.
Rachel described Rollo as "mangy".
An abandoned puppy, Rachel rescued Rollo and kept him a secret from her abusive stepmother, who found the puppy and attempted to drown him. Rachel triggered and empowered Rollo. Unable to control him, he killed her stepmother, maimed her foster siblings and destroyed the house.
- It's likely that Rachel's power works better on wolves than dogs because of something to do with Rollo's species.