Egoyan's work has always dealt with such cases. Exotica (1994), the film that first gained him his fervent British fan base, dripped with sensual heat; but the real sweat came in wondering what horrible truth the schoolgirl-costumed stripper the protagonist visited would haul to the surface. In the Oscar-nominated The Sweet Hereafter (1998), a school bus full of children freezes under a lake, the pain of each parent lashed down deep. His films work in buried ways.
Today, Egoyan is greeting visitors in the bowels of English National Opera in London (where last year he directed Dr Ox's Experiment). He has a penetratingly curious gaze, a swift, open wit, and is altogether the gracious host. You'd never guess the oddness of his life, the strange memories secreted in each cranny of his films. Born in Egypt to Armenian parents in 1960, he went to Canada at the age of two, and seemed to set about constructing a new identity for himself. He forced himself to be Canadian.
In his very first film, Next of Kin (1984), a child takes on another's identity. In Felicia's Journey, more minutely, Hilditch is shown being used as a prop on his mother's TV show. As a child, it's recorded that Egoyan's architect father made him pretend to work at his desk when showing students round their house. He only sees the connection when I suggest it. It's the first of what will prove a flurry of unwilling revelations. First, though, we talk about a monster: Hilditch.
"He's a person who doesn't really remember his childhood at all," Egoyan said, enthusiastic. "He is in complete denial about how he is raised. You look at him and wonder, where are his feelings, where are they located? When he's in his garden near the end with two religious zealots, and he says 'I'm not in pain, I don't know what you mean by pain', it's true. These women have no idea that they're in this garden of bodies. Yet in his mind he's not a monster. He's the nicest man in the world."
The way Hilditch seals over parts of himself he doesn't want to face, composting them like the corpses in his garden, irresistibly recalls what seems Egoyan's life-founding fact, his willed denial of his parents' culture. But at the mention of this his defences immediately rise.
"That is an overwhelmingly obvious aspect of my childhood," he says, voice cooling, careful. "I remember my parents were unable to keep me speaking their language. I think what I went through is in some ways the Canadian dream, the assimilationist dream, that you can come to a country and become a functioning member of it. I'm a model example. The idea of someone like Hilditch, a person who pretends to be someone they're not and is rewarded for that, has always fascinated me. As long as you're not harming others, what is the advantage of living in the truth?"
I am reminded of his comment that his characters are "mysteries to themselves". Is Egoyan then a mystery to himself in some important way - a part of his heart buried with his Armenian roots? This, it transpires, is a step too far.
"Well you see, even the discomfort I'm feeling right now in answering that question is a form of denial," Egoyan says, cracking. "I don't want to get in to that, because I don't want to make such a big thing of it. Because I would like to think that you see me as someone who's completely assimilated. And suddenly, here you are asking me these ..." He breaks off. "In Canada, you are expected to feel comfortable being somewhere else. When I'm there, it's not brought up a lot."
He starts to talk about his experience of Oscar night, when proud Armenians questioned him in his abandoned mother tongue. And then the very last questioner asked how he felt as an African film-maker. It took him a moment to remember he was born in Egypt.
Is Egoyan's racial past really so mysterious to him, I ask - is his identity really so ambiguous? "Yeah, it's fascinating," he says. "Because it happens all the time in LA, that people project that I'm Jewish. And in the entertainment field, I feel things are facilitated by my not contradicting them. In a way, I completely understand the Jewish experience, because Armenians have been oppressed and have gone through a genocide, everything that from my point of view it means to be Jewish I understand. So there's no point in my saying I'm not."
One of the terrors of watching the protagonist of Exotica is that he may be a paedophile, while in The Sweet Hereafter a girl and her father commit an act of strangely muted incest. In Felicia's Journey, too, Hilditch is a grisly father-figure to a teenage innocent. I've read that Egoyan's first girlfriend was abused, undetected, by her father for years, and there's no question of his sympathy for such tragedies. But his work walks more dangerous ground.
"I think the deep, dirty secret about incest is that, in some cases, there is consent," he says carefully. "The issue then becomes, does that person have the wherewithal to make that consent? One of the things that is provocative about The Sweet Hereafter, for instance, is that it's about an incestuous relationship told from the point of view of that victim as it's happening, when she does feel that it's an extension of the father's love. I'm not trying to normalise it, not at all. There are other situations that are more clearly monstrous, where it's just about a parent exerting violent authority and control, and those are easy to label, easy to condemn. But there are situations, as in Exotica, as in The Sweet Hereafter, which are more complex. My job as a film-maker is to show what it means to be in that place. That's what matters."
The films from Exotica on are notable for another thing - a growing warmth. Egoyan has said of his early films that they were about "emotions so strong, they had to be contained". Does the emotional release in his recent work come from a personal change? Has making them helped him heal himself?
"Well, again," he says, "I like to think that I'm functioning and that I'm healed. But there are things I do, especially to people I'm close to, that make it really obvious there are darker issues I haven't resolved. There are things that happened in my personal life, very recently, which make me realise there's something in me that's quite f---ed up. I think the work becomes even more frustrating to those people that you're close to that you're hurting. Because they go, 'Why is it that you can deal with those issues and make these beautiful testaments, and then act so differently?' and I can't answer them."
'Felicia's Journey' (12) opens on 8 October. 'Formulas for Seduction', a documentary about Egoyan's life and work, opens at the Curzon Soho, W1 (0171 439 4805 on 10 October