She is most noticeable by her clothes, her appearance, and even the way she carries her books. For one particular episode, Curse of the Looking Glass, she became Darlene, a very beautiful girl whose looks were irresistible to other males, however, the drawback of her wish was that every boy she touched was turned into a crispangore, and only self-esteem tips from Diana convinced Darla to reverse her wish.
Darla is slender with fair skin, green eyes, long red-brown hair, and normal pink lips.
As a stereotypical nerd girl, she wears pink glasses, pink long-sleeved jacket with medium pink, white and gray borders on her V-neck and short sleeves and a white collared long sleeved shirt, raspberry skirt with a light pink border and primrose Mary Jane shoes with white socks.
Also, as a beautiful girl whose looks were irresistible to other males, she wears a robin's egg blue and pink bordered (with a ribbon) half-sleeved strapless shirt with her belly showing, a robin's egg skirt that wears a pink belt with a white heart symbol in it and long and short robin's egg blue socks with pink boots. She carries a primrose plum-purple school bag and she no longer wears glasses.
- She appears frequently as a background character for the third season.
- She has made a cameo in Totally Spies: The Movie.