A part of the Wonderland Gang, Tweedle Dee and Tweedle Dum joined the Mad Hatter on several of his missions. Almost always, they were defeated. Dee and Dum were not confined the Arkham Asylum, but rather Blackgate Penitentiary. Due to criminal connections, they almost always managed to escape, but were interrogated by the Batman and sent back to prison. After the Crime Syndicate took over, the two cousins joined the Secret Society.