Well... I will write as much as I have come up with so far.
Name: Nancy but in her Naga-form, Legna.
Gender: Female.
Specie: Cryptid: Naga.
Age: Same as Zak Saturday.
Haircolor: Silverblond.
Eye-color: Green.
Color on the snake-body: Golden.
Height: Same as Zak Saturday.
Weight: 25 pounds.
Powers: Has the ability to change form. She can turn herself in to a human and even a Pokemon. She is also a skilled swimmer and can easily climb up a wall.
Weakness: If she is in her Naga-form (the original one), she cant stand the cold.
Background: Legnas egg was stolen many years ago by a scientist and luckily for him, the Nagas hasnt found out about it yet. The egg (which was golden with jewels on it) hatched the same day as Zak was born. The scientist that stole the egg came from The Secret Scientists and the reason he stole the egg, was that he wanted to study a Naga up-close. His name is Dr. Yoshim. Legna has grown up among humans and doesnt want to understand that she is a cryptid. But when V.V Argost shows up and tries to kidnap her, she is saved by the Saturdays & by Tak. Zak and Tak manages to convince Legna that she is a cryptid and NOT a human. But since Legna has gotten used to live with humans, she cant return to the other Nagas. She instead joins forces with the Secret Saturdays.
Well... Thats all I have come up with for now. When I have the time, I will try to draw a picture of her.