So, finally developed a short profile for her... thoughts are appreciated.
Leviathan Mermaid
Size: 620 feet
Hair: Light Blue
Eyes: Purple
Skin/Tail: Tan/Purple and Light Blue
Calico is one the handful of Leviathans living deep beneath the Topazial Sea, and is very kind, particularly to those caught adrift and alone on the open waters. Like the rest of her kind, she is quite old-- even as one of the youngest of her race, she is still almost two centuries old-- and thus is well aware of the dangers that await the lone sailor on the open ocean.
Unlike most of her kind, though, Calico's sense of balance is damaged. A fight with a pack of orcamaids as a child injured her severely, nearly tearing apart one of her ears, as well as other wounds. The injuries have healed over time, the scaring mostly hidden by her mass of hair. The bleeding, however, as well as tissue damage have permanently ruined her sense of direction.
As such, she often runs into ships on the surface, and at her size, the impact is often devastating. Her disability causes her a great deal of grief, and she often goes out of her way to save the victims of her accidents, swallowing whole groups of lifeboats in order to ferry them safely to shore. While initially terrifying for the passengers in question, they eventually are greatful for her help, and are usually willing to forgive her for the accident.
Incidently, her accident-prone nature, and hurried swallowing of passengers, also means that she catches a great deal of cargo from these wrecks. Her forestomach is thus laden with treasuers that settled, and never passed through the rest of her digestive system. Anyone willing to venture inside to recover some of it would find themselves fabulously rich, although getting things back out again is a trick no one has been able to manage thus far.
Calico is extremely friendly towards humans, and loves to talk to them, as well as carry them with her. Her relations with other mermaids are lukewarm at best-- she rarely meets any of them, and is generally slow to trust most of them, given how violently she was attacked as a child. Also owing to this attack, she is particularly fierce in attacking any threat to herself, her guests, or her school, relying on her strong arms and sharp teeth to crush or tear apart anything persistant in attacking her-- if her attacker is small enough, she may just choose to swallow them alive, letting them digest alive within her main stomach.
Her relations with humans, though, are purely ocean-going: due to her enormous size, she can't approach land very closely without beaching herself. Thus, she is incapable of traveling inland, and can only approach beaches with some effort. Still, she tries as best as she can, out of a desire to learn more about the world outside of the ocean depths.