My son is 15 months old.
He's always been rather huffy if he gets bored, which happens verily quickly if he's restricted to his high chair for example.
However the last few weeks he's had such a change in temperament! He's just one big walking huff. He screams if he doesn't get his own way, he kicks, he trashes, he throws things. He cries (no tears).
Is he just learning he can test me? I wasn't expecting this for another year!