Im usually not big on fan-fic but we have quality writing right here on Gamespot. Life in the Mists, created by Gamespot user Ferran, is fan fiction set in the Half Life universe. It follows the expliots and trials of Carl and his brother Paul in a city that has undergone major Shelling by the Combine.Whether your a fan of the Half Life series or know very little about it, Life in the Mists is a great read that I highly recommend to anyone.

http://www.gamespot.com/pages/unions/read_article.php?topic_id=20412381&union_id=55 - Link to fan fiction section of HCU, has Chapters 1-3

http://www.gamespot.com/pages/unions/forums/show_msgs.php?topic_id=25185153&union_id=55 - Link to Chapter 4