I mean, if you have been a step-parent to Sid since he was little and you did your job well you will have established a good parent/child relationship. This relationship has put you both on a firm foundation and is likely to help you both through the hormonal confusion of the teen age years. Don't forget, by the time he is a teenager you will be older and wiser too!
Remembering your own teenage struggles will help you relate, at least a little, to your own teenagers. How troublesome were you. Actually you were probably perfect it was your parents who had the problem - if you see what I mean. What was it about you and your teenage antics that riled your parents so? Who was it that made you so angry? Why was that? Was it just your mood or can you pinpoint something that triggered a reaction in you?
Support networks are essential. What kind of support and solace did you seek when you were a teenager? Your teenager is likely to want some privacy too. This is not to say that your step child will have the same experience but rather, with hindsight you may be able to understand his needs a little more. By trying to understand and give him space within the boundaries you set for him you will not only survive Sid's teenage years, you will also come out smiling the other side - together.
Technically you are a step-parent but try and think of yourself as just a parent, who, like any other wants to do their best for their teenage son or daughter.