Because I was lacking a water-type in the 42, and in general, I decided to introduce this girl, whom I immediately loved, but not much backstory yet ^.^
This is Lucy, called Seven instead of her 'living name'. She's been with the 42 for langer than she is able to remember, and wouldn't be that bothered about remembering anyway.
Originally a Ditto, Lucy was raised by a family of water trypes, and grew to love them and their lifestyles so much that she eventually decided to become a Dewgong full-time, so much so that she forgot how to change back.
Seven lost her heart long ago enough to not be able to remember it clearly, so it's a blessing in a way. She is also one of the few members of the 42 whose Shadow has been destroyed completley.