Girl kisser

Eiru in her hero costume! Awesome costume design by @thequillpill

You know how when he uses his quirk there's a cloud of energy representing the person's quirk? What if that cloud is actually the base of the DNA that represents someone's quirk condensed into a cloud of energy.

I know this sounds crazy, but what if his actual quirk is transforming someone's quirk factor (their DNA) into energy and transferring it to something else before returning it to it's original state as DNA bases???

That would explain how he's able to modify and combine quirks. That would explain how he's able to experiment with quirk factors and clone them, he is sucking the DNA bases out of people in the form of clouds of energy and then returning it to it's original state to PHYSICALLY alter it. Or he could combine energies and then infusing it into people's DNA.