Greella is an Explorer. She's one of the Explorers Gang. She looks for hidden doors, old tunnels, secret gardens. And she tries to solve mysteries, like, what is the broken robot Achilles guarding behind that round golden door?
Not much more to say about her.
She's not very sociable, but that's really because she's often underground or in other "silent" places where chats don't carry. Not that she's unbearably shy or anything.