Mary decided to train and outfit herself as Roberta the Girl Wonder to join him as a Gotham based teen crime fighter in order for the two of them to meet. Despite Dick's initial reservations about "Roberta" after she sneaks into the trunk of the Batmobile and proves helpful, patient and quick witted on the case he was working on by acting as a waitress and patiently looking for an identifying bit of jewelry for several nights he slowly starts to warm up to her. They work together frequently on cases while Batman is out of town with Mary often working undercover in disguise but also fighting alongside Robin. After Robin is able to uncover "Roberta"'s identity as one of his classmates he becomes concerned about how secure his own identity would be if he were to reveal it to her and decides to try and discourage her from continuing to act as a costumed hero. His plan works a little too well as the substance to loosen her mask takes effect while they are on camera. A disappointed embarrassed Mary quickly says goodbye to him knowing her crime fighting career is over and never suspecting Robin was behind the public reveal of her identity.
- Acting: Mary was good enough at acting to hide her identity from her classmates with little else to disguise her beyond a domino mask and was considered the best actress in her drama class in high school, getting the role of Juliet in a class play.
- Chemistry: Mary is an exceptional young chemist with her own crime lab and ability to create her own smoke pellets.
- Lock Picking: Mary was able to pick the lock of the Batmobile's trunk and stow away inside.
- Photography: Mary had her own small darkroom in her parents' home for developing her own pictures. She converted it to a crime lab secure in the knowledge her parents wouldn't uncover the change due to their disinterest in photography.
- Sewing: Mary sewed her own "Roberta" costume.
- Crime Compact
- Batmobile: During her period as a crime fighter she was often driven around by Robin in the Batmobile.
- Smoke Pellets
- This version of Roberta the Girl Wonder, including all history and corresponding appearances, was erased from existence following the collapse of the original Multiverse in the 1985–86 Crisis on Infinite Earths limited series. Even though versions of the character may have since appeared, this information does not apply to those versions.
- 1 Appearances of Mary Wills (Earth-Two)
- 5 Images featuring Mary Wills (Earth-Two)
- 1 Quotations by or about Mary Wills (Earth-Two)
- Character Gallery: Mary Wills (Earth-Two)