He is the protagonist of the story, thrust into the mind-altering world of Silent Hill in order to confront his inner-demons and stop a terrible entity from being unleashed upon the world.
Eric is a 17-year old high school guy. While he is tall, thin, and handsome, he tends to keep to himself and has always been an introvert. Throughout the movie, he dons his apple-red hair and mostly wears a purple hoodie and tight blue-jeans (except for part 1).
He only has two true friends, which are Ashley Morris and Sherry Lockwood. Eric, just like Ashley, has always been known to look or act depressed, but he has never thought of himself as such.
*MAJOR SPOILERS AHEAD. READ AT YOUR OWN CAUTION.*
In the town of Silent Hill, there was a religious group of zealots known as The Order, who were witch-hunters. An innocent girl, named Alessa, was labeled a demon. She was continuously outcasted and abused by the people of the town, except for one child; Terri Bradshaw. Terri saw the good in Alessa and didn't understand why the townspeople hated her so much. He was her only light within such a dark world.
However, one day Alessa's mother was tricked into letting the townspeople burn Alessa alive, making her believe that it was simply a spiritual cleansing. Terri knew what was really going to happen, but his family and peers were done with him trying to "cohort with the devil" and threatened to burn him too if he tried to warn or save her. Terri had no choice but to let it happen. The worst was yet to come, though...
The night of the burning, Terri's parents forced him to come with. To Terri's absolute torment, he had to stand and watch as his poor friend, Alessa, was burned alive. When the fire spread and burned down the building however, Terri and his family were one of the many that night that died in the fire. The rest of the town and cult were thrust into an alternate dimension to be tormented by Alessa's rage for the next 20 years.
Alessa had a much more sinister plan, though. Her hatred for the world was so intense, that she came up with a dark plot to spread her power throughout the whole world and torment everyone, not just Silent Hill. In order to do this, every remnant of her pain and hatred must become one with her. So she separated her soul into two parts; the dark part and the good part. The good part of her soul was placed into that of a newborn baby, Sherry Lockwood, and sent into the world to live a normal life while the dark part lay dormant in Silent Hill. She then found the remains of Terri and used her powers to reincarnate his soul into a newborn baby as well, Eric Harmon.
Alessa knew that these new souls would one day be called back to Silent Hill and become one with her again, and then her power would be able to spread outside of Silent Hill and infect the whole world.
Eric grew up in a decent home with a slightly distant family. While they loved and cared for each other, as they all grew older they started to part ways more and more. At 17 years of age, with his dad out on work trips and his sister moving off to college for weeks at a time, Eric was spending a lot of his time by himself. However, he begins to start having dreams (and even seeing visions) of an evil world calling to him. This place, whatever it was, beckoned to him constantly. As it starts to affect his schoolwork and everyday life, he begins to make a resolve that he will travel to this strange place, Silent Hill, and figure out what it is that is haunting him.
But little does he know of the true horrors that will unfold around him as he ventures into the nightmare of Alessa's vengeance.