So I was thinking of little red riding hood story and was also looking at the league of legends character Annie, and thought wouldn't that be a cool concept in reverse?

So I was thinking of werewolf warlock it'd be an old lady, wearing the hood of little red riding hood like her grandma, and her story is that she's searching for her grand daughter. Who was Kidnapped by the werewolf she got lycanthropy from. Everytime she is transforming she hides behind a tree, and pulls out a puppet that looks like her, and puts the hood on it then cast the spell puppet on it, so that while she is a werewolf people would think that it's just a little wolf doll she reanimated into this big beast, and she tells people she only has the power to do this when the moon is visible. So even though it's strong, it takes concentration to use, which is why she can't cast any other spells. And she would keep up this Charade as long as possible. But she's sort of at a disadvantage cause she has to stay within 20 feet of the puppet, to ensure it isn't damaged by an enemy giving her away. But the second people find out she goes all out casting spells and attacking enemies while no longer having a reason to keep up the illusion.

I Sincerely doubt I will be able to play the character, so I might just make it a friendly npc that temporarily joins the party. In a Gothic inspired campaign I could write. How would you build this character to make it work? Or build it in a way it wouldn't be so powerful that a dm would say no to?