I don't remember why Nathan is sad here, but there are a few things I can tell you from looking at the the photos and videos next to it. I took Nathan and James out in the parking lot behind our house to ride scooters. Nathan spent a lot of that time running as fast as he can and jumping up onto the stone wall dividing the complex from the busy street. They were having LOADS of fun doing this.
So, why is Nathan so grumpy? That's an excellent question. This is a common problem with Nathan. He gets himself into these states...usually set off by something really little that didn't happen quite the way he wanted. Maybe he was trying to get James to do something, or maybe he didn't run quite as fast as he wanted, or maybe he bumped his finger on the wall. It's impossible to tell. The thing is, it doesn't matter what it was, Nathan is determined to let that small thing ruin the rest of his day. Here is Nathan sporting his wallowing face. It's still so very beautiful.