For his second Halloween Harvey was a mouse. He thought he looked pretty cute: he told us so every time he looked in the mirror.
He was a little bit uncertain about the actual trick-or-treating part, until he found out that he would be getting actual candy that he could actually eat (in representative quantities at least). He still wouldn't put his own hand out to take anything, but at least he consented to being carried up to a few peoples' doors.
Now we see how well he sleeps after consuming as much candy as he has. Or coo-key?!, as he describes it.