Halloween & A Sharpie

I just came in here to try to calm down. I put C down for nap an hour ago and then he had to go the bathroom and then he was up playing and then... I got busy with K's piano practice. Even though I could hear him in his room talking, I decided I'd go up in a minute. Well, I came up and he had crawled on top of his dresser, found the Sharpie pen I had hidden there next to a stack of hand me downs. I was marking initials on the clothes. (The pen has been there for months, he's the 7th grandson on D's side of the family and as the seasons are changing we're getting clothes from 3 cousins and passing down to a cousin.) He marked all over himself, his dresser, his walls. I'm not sure where else b/c I lost it. He started crying and I put him to bed and closed the door. I'm just not ready to deal with it. What's the proper punishment? I left the pen there. The dresser is about 4 feet high but he can climb up on it from his bed BUT he's never done that prior to today. Tonight is Halloween, should he have to stay in? That seems extreme but he knows not to draw on the walls. It's quiet in there now. The only good thing is we're planning on painting his room in the next month or so. I'm still trying to pick out colors and sheets.

Halloween starts in an hour. I'm ready for it to be over, we've had so many parties and costume wearing occasions, I'm worn out.