Remus Lupin wrapped his arms around his body self-consciously and stared out the window at the passing countryside. This would be his first year at Hogwarts, and he was nervous. Certainly all of the first years on the train bound for Hogwarts school of witchcraft and wizardry were nervous, but not like Remus Lupin was. After all, he had special circumstances to deal with that would make him more worry-prone and nervous than the rest of Hogwarts' incoming first years. Because you see, Remus Lupin was a werewolf. This did not by any means make him a bad person; on the contrary he was sweet, affectionate, shy and kind, but other people didn't see that once they learned the werewolf part. Perhaps you are not sure what a werewolf is, so I will explain to the best of my meager ability, though it is not a concept that is particularly difficult to grasp.
A werewolf, in a way is part wolf and part human. No, they don't have the body of a wolf and the head of a human as a sphinx is the body of a lion and the head of woman. They simply undergo a drastic change on a full moon. They go from being human to wolf; though certainly not a normal wolf which walks on all fours and is mostly unthreatening; no, no, no. You see, werewolves are quite spectacular creatures as they are still part human, though they certainly possess the not-so-good side of humanity as it stands. They can be quite deadly, and get quite awful cases of blood lust, which compel them to set out and kill, or at least scratch, bite and generally mutilate any viable living things, markedly people. The other most intriguing thing about a werewolf is that if someone were to be scratched or bitten by one of these super-strong creatures, they themselves would become a werewolf. This is how young Remus Lupin's particular predicament came about. I, myself am not versed in the particular circumstances that came about to Remus' life-time membership to the werewolves club, but I do know that he was bitten when he was rather young. Now, as things would have it, Dumbledore-the Headmaster of Hogwarts-of course knows this, but the student body-of course-does not. So as you can see, Remus Lupin has a very special circumstantial reason in which to be self-conscious, worry-prone and nervous on his first train ride to Hogwarts.
Now perhaps you do not fully understand exactly what Hogwarts is either, and though I could spend a great amount of time bringing you up to date on the wonder that is Hogwarts and its long long history-as I do know most of it-I think you would bore quickly on such a topic and since someone else will write a full text on it, I would direct you to "Hogwarts, A History" that will be made available in about fifteen years or so.
Despite my rambling, this is a tale of Remus Lupin and his soon to be friends-as well as soon to be enemies'-seven year trek through Hogwarts School of Witchcraft and Wizardry.