As the title suggests, this is an another analysis of the endings, one that uses the characters as major reference points.
I believe that the characters in the game, in addition to their own self-contained stories and importances, are also an array of attributes that symbolize the various paths James can take upon his journey.
LEAVE = Laura
The idea is pretty obvious, but there is more to it than just the idea that Laura leaves with James in the ending. Laura typifies the very essence of the Leave ending.
In Leave, James never falters in his desire to find his wife, and is steadfast in his search to find her. He keeps Maria at arm's length, and doesn't waste too much time thinking of himself. Mary is the goal, therefore, she is the most important. In Leave, James finally has the opportunity to spend a last moment with Mary, to be able to say the things he didn't say before, the things he couldn't say or wouldn't say. He abases himself before her, and flings aside all vestiges of the delusion he used to hide himself from reality. Because he commits to this course of action out of a deep and abiding love, and because he forces himself to come to terms with his own troubled thoughts, voicing them out loud for her to hear, Mary forgives James and puts his mind to rest. When last we see James, he is walking through the cemetery towards the scenic turnout, and we see Laura following closely behind. As one of Mary's letters made clear, Mary wished to adopt Laura as her own daughter but could not. Though it is not stated for certain this is what happens, to me it is implied that James decides to do just that, both out of respect for his wife, and perhaps as a thanks to Laura herself... because out of every character, Laura is by far the most influential in aiming him towards this conclusion.
Laura is in town for the same reason as James; she wishes to find Mary. She is, at first, uncertain of James' motives, for she believes James to be an uncaring, selfish lout (and at first he does little to correct her notions). She realizes that there is more to him than meets the eye eventually, and by the time both reach the Lakeview Hotel, Laura is more pleasant to James and openly assists him in their shared goal.
But, she is not just a tool for James. She is there for her reasons as well, and would just as soon prefer James to not be an interference. Yet, it is her actions which guide him on the proper path, bringing him to the Hospital when no other course of action seems viable for James to reach the hotel. This sets in motion a chain of events that leads him where he wants to go, but in a most roundabout way.
Indeed, she is completely indicative of the ending, because her goal completely typifies the context of Leave: Find Mary, and never falter while looking. She never does. Presumably, she finds Mary (because, otherwise, there would be no way she'd go along with James. Undoubtly, they had their own private moment too, where Mary told her things about James that made her overcome the incredible anger and hate she displays in room 312.)
IN WATER = Angela
Another really simple one, perhaps the simplest; for both come to a very similar end and parallel in other ways. Both James and Angela commit acts which are violent and deadly. Both can suitably justify their deeds if either desired to. The problem here is that neither wishes to justify. Justification would lead in a very different direction. Instead, both decide that instead of vindication, they deserve punishment instead. Both desire punishment, but neither possesses a full-blown deathwish until the end, when all hope is truly lost. Of all the supporting characters, Angela's ultimate purpose is the least clear, and this is because she has none at all. Like James, Angela does not desire her own death from the beginning (this is evident in the Blue Creek encounter, when Angela surrenders her knife to James. She pointedly states she is doing so to prevent unpleasant things, and considering her position when we find her in that room, the 'unpleasant thing' is very clearly suicide.) Perhaps she still holds hope for redemption of some kind, or perhaps she has just not resigned herself to the inevitable. Regardless, by the end, she has. Whether she dies on the stairs of fire are not clear, but certainly, no other end is likely. Either she will die or wander endlessly, dead in spirit and soul, if not in body.
This is analogous to James in the same role. He does not begin with a deathwish. In fact, the thought never really seems to cross his mind. He will expressly deny thoughts of suicide when Angela makes a remark. But, in the end, he has his moment with Mary, in which he gets to clear his conscience. But, his eyes are opened to the truth, and even though his conscience is clear, all that does is expose him to the rest of the truth, about himself and his life. He loves Mary. Deeply. To the point where he decides that he cannot live without her. He surrenders notions of life and future. Possibly, it is a gambit, to see if he might find Mary in the afterlife, but the underlying fact is that he has given up on life, just as Angela has. It's not a desire to kill himself, but rather a lack of desire to continue living.
MARIA = Eddie
Now the territory is not so clear, and since I use Maria as an example for a different ending, you might just cry foul. But, the Maria ending really isn't about Maria, it's about James, as all endings are. In the Maria ending, James does falter in his search for Mary, and falters badly. Maria is a seductress, a lookalike of his wife designed by his repressor mind to cling to the delusion in which he spends much of the story. Maria's appearance and personality are contrasted to Mary in several key ways, yet retaining a painfully obvious familiarity. She is, perhaps, the ideal Mary, especially in contrast to her later days. She is attractive, energetic, provocative and, in some ways, as caring and empathetic as Mary. She is the Siren of his delusional mind, seeking to retain its existence.
What Maria also signifies is James' surrender to his desires. This isn't just a carnal statement, though that is likely a part of it. Certainly, he desires sex. Most people do, and her appearance is a reflection of it. However, there's more to it than that. She is real, to James. She isn't Mary, but maybe she's close enough? Maybe, with Maria, James can have everything back that he lost with Mary's illness and death? Not just sex, but companionship, togetherness. An emotional bond. Love, even. A replacement for his wife, as close as one can get.
Now, how does Eddie factor?
Well, he has desires, too. His desire is vengeance. He views himself as the avenging angel, and considering his state of mind in the final encounter, it's not a new concept to him. For years he has desired to lash out against those he considers his tormentors, to visit upon them the suffering and pain he feels he has recieved. It is perhaps this thinking come to a head that results in his murder of a dog, and the subsequent maiming of its presumed owner. He has a taste of the Avenging Angel, but it's a bitter taste at first. His moment of dominance is fleeting, for the law will be far more dominant than he, or any of his oppressors. Thus, he escapes to Silent Hill, a place that shows him things that torment him as badly as anyone he has encountered in his life.
What Silent Hill also offers is the chance to strike back at this percieved oppression, in the same manner as what brought him here. He kills those who laugh at him. Whether or not they actually do is irrelevant, because Eddie is going to assume the worst. It's a natural response for someone of his mindset. At first, his exercise of this control is unnatural to him and he is unsure of how to react. Except, this time, there is no law to fear, there is no stronger and more dominant force to stop him. He is the law now, and by the end, he is a man without mercy. He has surrendered to his delusional thinking, that everyone is out to get him. He has surrendered, but he's glad to have done it, because now, those thoughts of vengeance that have been brewing in him for his entire life are no longer an urge he needs to supress. He is allowed to do what he wants, and he is going to take it for everything it's worth. Like James, Eddie goes down the wrong path out of selfish desires and skewed priorities. Eddie's decision ultimately destroys him. James' do not, at least right away. The final scenes of the Maria ending very strongly imply that such a fate is all but inevitable, that he is doomed to repeat his tragedy, as Eddie did with his attack on the dog, and that the conclusion is going to be far from ideal.
REBIRTH = Maria
This one is actually more obvious than it looks, and it has less to do with Maria's character traits than her origins.
The obvious connection is the concept of rebirth itself. Maria is reborn twice in the game after being quite noticeably dead.
However, the strongest indicator is her origin story, "Born From a Wish" which is very heavy with references to the Rebirth Ending. She begins with no coherent memory or even a real identity. She knows her name, and has a grasp on her situation, but little else. Wandering around more or less aimlessly, she finds the spirit of Ernest Baldwin in his eponymous mansion. Searching this mansion leads her to discover the fate of Amy Baldwin, Ernest's daughter. Ernest decides that the only way he can find peace is to bring his daughter back to life, by performing a sacred ceremony using occult items.
In actuality, Ernest is more symbolic than Maria for this purpose, but it is Maria who acts as a tool to further Ernest's wishes, rather than her own person. Through her journey we learn much about the Ceremony of Resurrection of the Dead, and the items required to perform it. This is very important for James, even though he himself is ignorant of Maria's experience. I believe "Born" is the vehicle to better explain the mysterious fourth ending, and Maria's character is the vessel through which we experience this.