Izuku's quirk is Quirk Communication. It allows Izuku to communicate with the quirks around him, even if they aren't sentient. Each quirk is friendly towards Izuku as a side effect of this.
Every quirk has some level of sentience when Izuku is around. He can talk to them using a type of telepathy, and can even try to convince them not to activate. Unfortunately Izuku's own quirk merged with his conciousness when it manifested, meaning Quirk Communication the quirk is essentially dead. This is what left Izuku with the fascination for quirks he has in canon, as well as meaning Izuku can't communicate with his own quirk.
Unmanifested quirks speak like babies, babbling instead of speaking. Mutant Quirks are barely there, so infused with their weilder that all the can do is speak. They can't control themselves at all, as the weilder has more control over them then they do themselves.
Should Izuku get One for All, Izuku can communicate with the Vestiges as well as the quirks themselves 24/7. All For One is like a nightmare to Izuku. Constant screaming and agony do those quirks feel. They also hate the fact they left their weilder and are also highly likely to rebel if asked.
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MHA Story And Quirk Ideas
FantasyStory/Plot and Quirk Ideas I have no motivation to make, but think sound really cool! The entries with Quirk : [Name Here] means this entry is about a quirk idea! The entries with Story: [Name Here] means it's a story idea! If they're combined, it m...