Heroin, cocaine, ecstasy, and prescription painkillers are all a recipe for disaster for him and for you. It is only a matter of time before he introduces you to his "friends" (not really friends.. they're drug buddies) and gets you involved. I can't tell you how many people I know that have fought drug addiction and lost by either relapsing or dying. I also can tell you how many people I know who said "I will never do anything like that..." who then got a BF/GF, tried the drugs that they were doing and got hooked themselves.
NOTHING GOOD WILL COME FROM THIS SITUATION. Take it from someone who knows.
He is already hooked to heroin and most likely coke as well, since they go hand in hand. It's only a matter of time before he either looses his job or can't get a job because of his habit. Next thing you know, he will be borrowing money from you to support his habit. Then he will start owing dealers money. Then he will start stealing things to get money for the dope and the people he owes the money to. Then he will go to jail.
That is the usual cycle of life for people addicted to drugs. Notice how there is nothing good in the above paragraph.
You never get over a heroin addiction.
Look, you're 16 years old. You really shouldn't be hanging out with people who are doing drugs. Let me tell you, from personal experience, they will drag you down with them... slowly.
I got lucky because I some how managed to wake up and see what was going on around me and get out. My other friends were not as lucky. I lost one of my best friends to a drug overdose. All of my friends have been to jail, some of them multiple times. I don't talk to any of them anymore and my life is so much more interesting and meaningful.
The sad part is.. I was so messed up through high school and part of college, I can't remember much of anything. Those are supposed to be the good parts of life and I pretty much missed out on all of it because all I cared about was getting high, or drunk, or whatever. I didn't make me "cool". It made me a junkie.
Don't let that happen to you. Enjoy your life and make memories with your friends. High school is a time to have fun, not to get f-ed up.
Stay away from this dude because he will bring you nothing but trouble.