Greta is the daughter of Arianrhod, the Goddess of the Moon. Her father is unknown, but rumor has it, he might've been a druid. Despite being the child of a Goddess, Greta's powers didn't come about till she was a preteen. The only power she knows of at present is the power to make the moon rise and set... (which in turn controls the tide) unfortunately, she's botched that up numerous times, either by making the moon rise too early, having it set too late or forgetting to call for it at all, (she's terrible when it comes to being on time) resulting in weird moon phases and tidal patterns. Arianrhod hopes Greta will learn to get this right and more at this school she was sent to, partly because one day, Greta is destined to take her mother's place.
She's friendly towards most people and is always willing to make new friends, with the exception of anyone whom she senses could be dangerous, but she's not always right when she tries to read people. She also can be a bit moody when it's a full moon and is prone to become irritated when there's too many sunny days. (Being the daughter of a moon goddess, it's understandable.) She's usually more cheerful at night (and a bit more mischievous, but not in a mean-spirited way) or on (partly) cloudy/rainy days.
Science - Jack Skellington
Ethics - Phillip