My son sounds very similar to yours. He was a great baby and gave us no trouble at all from birth to 15 months. At 15 months his behavior deteriorated rapidly. We tried time-out, but it didn’t work. He would not sit in the time out spot. No matter how many times I kept putting him back there, he would immediately try to leave. After some months of that, we started putting him in the pack-n-play for time out. He would continually try to climb out. I then gave in and tried spanking even though I really didn’t want to go that route. Here is an example of a typical situation with him since about 2 yrs old. He is doing something he should not be doing. Me,”Please stop whatever it is that he shouldn’t be doing”. He continues/no change. Me, “I’m going to count to three and if you don’t stop doing that by the time I get to three, then I am going to spank you and put you in your room”. He still continues/ no change. I start counting, and reach three with still no change from him. I then spank him and put him in his room. He wants to win even though it means he will lose. From what I have read on the internet, he is just a very strong willed child. He is 3.5 yrs old now, and actually starting getting a little better right about the time he turned three, and continues to slowly get better. It was hell though from 15 months until 3 yrs old. We still occasionally have really bad days or bad moments during the day though now.