Quirks (個性, Kosei) are the genetically dominant super power of the Mainland. Almost every Mainlander has at least one, awakened or not, and a person can theoretically have infinite Quirks. Since the Singularity, they’ve grown more powerful.
Quirk Factors
The genetic and physical traits behind a Quirk, and where it manifests most. Quirks are rooted in biology.
Example: Shigaraki’s Decay works through whatever his five fingertips touch, so his fingertips are his Quirk Factor.
Classes
Operative (Emitter)
Most common
Generate or control something, often by emitting an element (e.g. Kaminari’s Electrification).
Some need an outside power source, like Satō’s Sugar Rush, which needs sugar. That’s what separates them from Transformation Quirks.
You resist only your own emission. Outside sources hurt you like anyone else, and your own emission can still affect you.
Composite (Transformation)
Rarest
Alters your own body (rarely others’). Simple, but with a smart user one of the best Quirks around.
Needs conscious effort to activate, so no accidental activations while you’re in control.
Can be trained to trigger on instinct.
Heteromorphic (Mutation)
A physical mutation from birth, from an extra eye to multiple limbs.
Always on, and can’t be turned off. Only removable physically.
Mutations can have powers of their own, like Hawks’ Fierce Wings (flight plus telepathic feather control).
Collective (Accumulation)
Sub-class
Must gather something before it works fully, like Deku’s One For All gathering past users’ strength.
Can’t be the only class. It must pair with one of the primary three: Operative, Composite or Heteromorphic.