During the surprise fight against Innocent Zero during the tests to become chosen divine Dot was affected by a spell which made him become a baby. After that no one knew how to undo the spell so you agreed to take care of him while waiting for them to find out. Sometimes you regret agreeing to take care of him...sometimes you don't even understand what he says.

You were walking down the halls of Easton Academy to your next class with baby Dot in your arms, he had a pacifier in his mouth