"Look! He's Purple! Without Green!?!?!"
Adam is an engine on the Island Of Sodor Narrow Gauge part. Thomas at first said the Adam was rubish and was a joker for at least half of Season #1.
Adam was ment in the stories to cause fights but, never did cause fights and became friendly and stop fights instead of that.
Adam is loyal and friendly - even James, who was the last to accept purple colored engines, couldn't help but like him.