A bard, cleric, mage, fighter our sorcer

The idea of a Thief not fitting into the storyline is absurd. Of course, I have a hard time imagining Gorion raising up Elves, Dwarves, or even Gnomes, a Thief is possible. Now Elves are considered 'young' when they are in their 50's or 60's, right? An Elf could fit into the storyline, as most Elves are too immature to survive on themselves before they reach adulthood. I'm playing, right now (BG1), an Elf Thief (Assassin). Think of it like this: You have been studying the way of the Thief so long, that you have passed your knowledge down to Imoen when you met her. Since she is another destined, she takes on the role, naturally. In the end, any character would best fit into the storyline, you just have to think of background. I've read some of Book 1 of the IWD trilogy, and Bruenor takes in a human, Wulfgar. So why can't a human take in another race besides human or half-elf? Just be creative, and you'll find that almost anyone can fit into the story.