That's going to require some editing on my part, but I can offer suggestions:<br/><br/>Instead of a Slime or Water Spirit, how about she is a human that comes from a long line of Water mages and possesses the rare ability to liquefy her body for a limited time?  Her family isn't famous or extremely powerful, but they are known for exclusively using water magic.  She can still be looking to find a place in the world.