We had no one else to learn this from- none of our parents were shining examples of relationship success- so we learned this from each other: when someone you love needs you to, you can get a hold of your five-alarm temper, get a hold of the shapeless things that scare you senseless, act like an adult instead of the Cro-Magnon teenager you are, you can do a million things you never saw coming.

Privately, I consider religion to be a load of bollocks, but when you have a sobbing five year old wanting to know what happened to her hamster, you develop an instant belief in anything that dissolves some of the heartbreak off her face.

What I warn you to remember is that I am a detective. Our relationship with truth is fundamental but cracked, refracting confusingly like fragmented glass. It is the core of our careers, the endgame of every move we make, and we pursue it with strategies painstakingly constructed of lies and concealment and every variation on deception.

Have you noticed how easily the very young die? They make the best martyrs for any cause, the best soldiers, the best suicides. It's because they're held here so lightly: they haven't yet accumulated loves and responsibilities and commitments and all the things that tie us securely to this world. They can let go of it as easily and simply as lifting a finger. But as you get older, you begin to find things that are worth holding onto, forever.

People need a moral code, to help them make decisions. All this bio-yogurt virtue and financial self-righteousness are just filling the gap in the market. But the problem is that it's all backwards. It's not that you do the right thing and hope it pays off; the morally right thing is by definition the thing that gives the biggest payoff.

But this is what I know about people getting ready to walk of the edge of their own lives: they want someone to know how they got there. Maybe they want to know that when they dissolve into earth and water, that last fragment will be saved, held in some corner of someone's mind; or maybe all they want is a chance to dump it pulsing and bloody into someone else's hands, so it won't weigh them down on the journey. They want to leave their stories behind. No one in all the world knows that better than I do.

When we can't see a pattern, we fit pieces together until one takes shape, because we have to.