I read a lot when I was younger, and there are a number of books and book series which I remember enjoying immensely, but I can now only remember bits and pieces from the stories, and of course can never remember anything useful like titles or authors. This makes it awfully difficult to track them down when I get the desire to do so, but I had some success tonight.
What I could remember:
1. It was a trilogy.
2. The main characters were kids or teenagers, and the books came from the 'young-adult' section of my local public library.
3. There were some alien creatures that roamed the earth in tripods. I remember thinking of them as Martians, because they remind me of War of the Worlds at the time, but I wasn't sure their origin was ever given.
4. The main character and a friend were intentionally captured, so they would be taken to the main alien city, where they would act as spies.
5. The city was not very conducive to human life, but many special steps were taken to make sure the human slaves could live anyway. One of the problems was the incredible heat; the humans were given salt sticks to suck on because they would lose too much salt from sweating otherwise.
6. The main character had a very kind and generous master, while his friend had a cruel master. The main character felt guilty because his friend seemed to acquire a lot more information inspite of his unfortunate condition. While I certainly knew a little about slavery, I hadn't ever had any serious thoughts on the subject. This was my first experience of the 'likeable slave master', where you can almost forget that the slave master is commiting one of the worst possible crimes. The main character kills his master when the two make their escape attempt, and I remember feeling sorry for the creature, and wondering whether or not I 'should 'feel that way.
That was about all I remembered, which makes me wonder if I actually read the whole trilogy, or just the second book from which all of that comes. Anyway, after a silly amount of time I found this:
en.wikipedia.org/wiki/The_Tripods