Sero is the kind of guy who goes by the phrase “Tape can fix anything”. Since he’s quirkless, this fits his personality. At some point, he got bit, leaving him under the influence of the infection. However, with help from Mina and Iida, he was able to control it. He very rarely goes ‘psych’, or zombie mode. But when he does, every stat (except Social Skills) is boosted to 5/5.