Crissy and Jannice Tilly were twin sisters with very different personalities. Crissy was a tomboy and grew up to be a fitness instructor. Jannice was the studious one and became an assistant DA in California. One day while they took a hike in Nevada they observed a shooting star land near them. When they investigated the crash site the cosmic energy fused both their bodies into one being. The Stark City Foundation found them and brought them to their lab to assist in their transition. They also provided a new identity for them and eventually moved them to their hero team The Star City Sentinels. As Solstice, CJ, as she/they now called herself/themself, found it difficult to focus with one sister in control. When Solstice’s adrenaline goes up, Crissy tends to dominate, when thinking is involved, Jannice tends to dominate. That does not always work out and the sisters fight over control all the time, often times switching in the middle of a battle. Solstice has five main powers, super strength (40 tons), flight, solar beams, invulnerability and healing. When Crissy is in control Solstice’s strength, solar beams and invulnerability are at their max. When Jannice is in control Solstice is not as strong or tough, but heals faster.