I'm sorry to hear you're having difficulty. It does take time to build relationships especially if you have expectations. Might i suggest you not compare, this man to your dad, the way he treats you to your sisters. Is there anything good that happens with your step dad? Things you can be happy about. Are there things you like to do together? Perhaps he's having as much trouble as you warming up? Does he have biological sons, maybe he's not sure how to be a dad to a boy he's suddenly supposed to care for.