Opinions on my extract please?

You've got potential here. I really like your vocabulary, and it flows well. The only critique I could give you is to make the dialogue sound a tad bit more natural. It's very good as it is, but some of it sounds a little too formal for a drunken/high person. I don't know how old they're supposed to be, but I get the impression that the older brother is around 17 and the younger brother is no older than 12; he seems sort of naive. If that was what you were going for, you did a good job.