Quirks mean everything in the world of My Hero Academia, and society has long since adapted to their existence. Meta abilities were rare and feared in the early days, though Destro's mother tried to sanitize them with the term "Quirk." Now, however, Quirks have become the norm -- and the small number of Quirkless people are being left behind.
It's even argued that a person's Quirk defines their entire personality, and lacking one can have the same effect. Izuku and All Might were both born Quirkless, as was Melissa Shield, a fascinating supporting character in the first My Hero Academia movie, Two Heroes. How different would Melissa's life be if she had been born with a Quirk after all?
If Melissa Shield Had A Quirk
Having a Quirk helps a person keep pace with MHA's unofficial, ability-based arms race of modern society, whether they are an aspiring hero, a budding criminal or an ordinary civilian. If the Quirk singularity hits, no one will want to be Quirkless in a world where society is falling apart and everyone is using their supernatural gifts with abandon. In such a scenario, someone like Melissa Shield would be nearly defenseless in personal combat. Then there's the societal stigma of lacking a Quirk, a total reversal of the early days of anti-Quirk discrimination. Melissa may be experiencing emotional distress from not having a Quirk, and she once dreamed of being a Pro Hero before abandoning that aspiration.
Some confirmed Quirks would benefit Melissa either for her lab work or personal protection, or even supporting heroes in the field. For example, Mei Hatsume's Quirk is Zoom, allowing her to focus on tiny or faraway items as though her eyes were natural microscopes or telescopes. As such, Mei can observe tiny components in her gadgets -- an ideal ability for a tinkerer like her or Melissa, the latter having designed the Full Gauntlet that Izuku used in My Hero Academia: Two Heroes.
Momo Yaoyorozu's Creation Quirk would allow Melissa to replicate any prototype item of hers to distribute to many heroes for testing, or replace one of her own damaged or lost inventions. She could also produce items made of rare and expensive metals or plastic this way, which would cut down on lab expenses. In emergencies, Melissa could use her creative and resourceful mind and the Creation Quirk to aid Pro Heroes in all sorts of ways, just as Momo does.
Nonviolent Quirks like these, or Erasure or even Brainwashing, would theoretically all fit Melissa's lack of combat training and her support role in the story, but does she absolutely need any of these? There are reasons why having a Quirk would actually slow her down, or would cause her to grow up differently and never become an ace inventor.
The True Role Of A Quirk In My Hero Academia
Melissa's advanced technical expertise allows her to support heroes in non-Quirk ways, and she has invented truly remarkable items despite not having Zoom or Creation to her name. She's already doing well for herself, and lacking a Quirk may have actually sharpened her personality and resolve. In My Hero Academia, having no Quirk is almost like a Quirk in itself, forcing a person like Melissa to focus on other endeavors such as scientific research, art, politics, bodybuilding and more, relying on nothing but her own ingenuity and creativity to succeed.
It's possible that with a Quirk, Melissa would have coasted or become complacent and not been quite so driven to succeed. Quirks are just tools, not a substitute for a smart mind or a good personality, and Melissa knows that just as well as Izuku. Even the strongest Quirks don't determine whether someone will become a hero or villain, or whether they'll succeed or fail in life. It's about what's on the inside, and that's why All Might chose Izuku to inherit One For All in the first place. In contexts like Melissa Shield and her father, Quirks are overrated. They haven't replaced the unique power of the human soul.