You're coming to see me at 2. I think I know why. You were guarded on the phone and a little more stiffly formal than usual, you who always were the most formal of my staff. I never knew whether it was just the natural manners of a well brought up young man or the age difference. Perhaps it was a lack of belief that you belonged among such political veterans as Josh and Toby. Fifteen years later, most of them spent in public office, and you still don't have their savvy or their flair for a fight. It isn't going to matter - they'll have your back in what's coming. Maybe it will be a good thing if sometimes they can't convince you about political expediency or about the need to get down as low as your opponents. Together you're going to have a hell of a game. They need the idealism that still shines out from you, even now you're battle-hardened, and you need to listen to them about the realities. You can't change the world if you never make it off the bench.

You asked for half an hour, but I've cleared my afternoon; if Delores Landringham was alive, she'd snort at that. I can see her looking at me with the look that always warned me not to get too far above myself. She'd be right, of course. A long-retired president who tends to fall over if he gets up without his stick is not actually in so much demand that it is a major feat of acrobatics to clear an afternoon for an old friend. Anyway, I've cleared it. I'd do more than that for you if you asked.

You didn't elaborate on why you wanted to see me but I do believe I know. We hear things even up here in New Hampshire, especially those of us with a granddaughter working in Washington. You're coming to ask for my blessing on your presidential campaign. You don't need it, but I understand why you'd ask. I would in your shoes. Abbey always likes to say that the two of us are very much alike - except, she will add, smirking at me, that Sam is much better looking. I'll give it, of course. You may not need it, but I'll give it with pleasure. I've seen you as my one-day-successor since a year or two into my first term. Did I decide that before or after I realised that that was Josh's plan? I'm not sure now. What I know is that I look at you and I see the conviction, the ideals, the intelligence, the courage and the truthfulness that America, may not deserve, but needs.

I've asked Abbey to give us the room when you come. Oh, she'll be back to share afternoon tea with us and to see if she can winkle any more information about Annie's love life out of you than she can find in her e-mails, but I need to talk to you first. You see, there's an apology I owe you. It's shameful that I've waited nearly twenty years and that now I'm hijacking your moment, but it's something I need to do. My father died with matters still between us - and between you and I, my dearly beloved adopted son, lays the thing never spoken of. I learnt the price of endless regrets when my father died; I will not allow you to pay it.

The minutes click slowly by and I get up and pace. It's not as easy or comforting to do as it once was, but I cannot simply sit there and wait. I don't know why I'm so nervous - you will never throw my words in my face the way Toby might; hell, the way Toby has done. It's not that you're soft - those of us, including the Democrat House Leaders, who have tried to turn you when you've made up your mind can testify to that - but you are gentle in its oldest of meanings. It was only much later and from others that I found out how angry and betrayed you had felt about the MS revelations. You continued to show me the same respect you had from the day Josh brought you along to the campaign office like a puppy that had followed him home.

Finally, the door to my library opens and Abbey ushers you in. There are shadows under your eyes as though you've been spending all the midnight hours plotting and planning - and you probably have, I don't believe Josh sleeps - but you look energised. Abbey leaves you with a kiss and it is my turn to greet you.

"President Bartlet," you say and hold out your hand.

I take it and then step in close enough to embrace you. Age teaches you some things; there is never anything shameful in love and there is never enough time to show that love. I held Leo that night in the car park, but I wish I had held him more often. I wish we could both have shaken off what our fathers taught us about being men. I wish your father could have spent more time loving you for what you are and less time telling you what you should achieve.

"Sam! Come in, sit down."

You do so, smiling at me a little uncertainly and taking your glasses off to fiddle with them for a moment.

"Sir, I've come… I wanted to…"

I interrupt you. "I know, I think. I need to talk to you first, though"

It's a little unreasonable, a little rude even given you made the appointment, but I was the president once so you simply nod and wait on my pleasure. Ellie would tell you that being president simply confirmed in my own mind that I was the most important person in the world and codified my inclination to bore people; I tell her that there had to be some benefits to a job that gets you shot and means you can't blow your nose without it being someone else's business.

"Sam, I should have done this a long time ago, but I want to apologise."

You start to speak - to decry this, I'm quite sure - but I raise my hand a little and you are obediently silent.

You are sitting facing me in one of the wing chairs by the fireplace and I lean forward a little and place my hand on your knee.

"I want to apologise for the lies I told you about the MS, and, yes, Sam, I do know that they were lies. I understand lies of omission. I lied to all of you and, worse, I led you into a situation where you were unwillingly and unknowingly made complicit. You all left jobs and lives behind you to come and work for the 'real thing' only to find out later that he hadn't trusted you, or the people with the truth. Not so real, after all."

Your eyes widen a little at my use of Josh's term. I guess you didn't know that I knew of it. Truth is I've known all along. Josh told Leo about it in his explanation of why he'd turned up trailing you, and Leo passed it on to me. Wily operative that he was, he knew it would stiffen me in those early days when walking away was such a tempting option.

I stop and sit back. I watch you for a moment. You swallow and say quietly,

"It's all right."

I shake my head.

"No, it really isn't. I lied to you and you have every right to be angry about that. Your trust was betrayed, Sam."

I pause and look at you again and this time you nod. My heart turns over at the hurt I glimpse in your eyes. You don't deserve what we've done to you. Both of your fathers lied to you and yet somehow you still find the strength of heart to trust.

"Worst of all I wasn't brave enough to face you and tell you myself. I let myself hide behind Leo's concern, and of all the things I asked Leo to do for me that's the one I regret."

I wait for a response but you are looking at the fire, not at me.

"Toby told me a few years ago how much I hurt you."

"He shouldn't have," you say flatly.

"I've wanted to apologise for a long time but there never seemed to be the right moment… of course my wife would say I'm just a coward looking for excuses and it could be that she'd be right."

I don't get the laugh from you that I hoped for - not even a twist of a smile.

"Anyway, when you asked to come and see me, I knew I needed to get this cleared away."

I move forward so our knees are almost touching and wait for you to look at me again. I make my voice quiet so you will have to concentrate to hear me - I need you to hear this.

"Sam, I didn't tell you because I just couldn't bear to. Not because you didn't matter or whatever stupid reason you've made up. Because I couldn't bear to see the scorn in your eyes and to know that I'd broken your trust. I made Leo do it because your opinion mattered that much to me."

You rub your hand across your eyes and I take your other hand.

"There are no easy tells; not a one of them. Toby was furious… and I think you know what a biting tongue he has when he's mad. CJ cried and it felt like it did when I had to tell my daughters. She kept patting my arm until she remembered that I was the president. Josh… Josh looked at Leo. He knew what I'd done to him. Then he started talking strategy."

You almost smile.

"That's Josh."

"I knew I'd hurt the others and let them down. I'd lied to them just as much as I'd lied to you, but you were different. You were the one who really believed we could make a difference. Maybe it was because you were younger, or because you hadn't been in politics before… or maybe you needed to prove that things could be about more than money and success after New York. Whatever, Sam, I just couldn't bear to face you and see you lose your faith. I let Leo take that bullet for me instead and that wasn't fair."

I pause to take a breath. You don't say anything, but you grip my hand more tightly.

"I never faced you and apologised or listened to what you had to say… and then I took your continuing loyalty as a gift. I didn't deserve it."

"Don't ever say that," you say, suddenly fierce.

You wipe your face again and glare at me with that stubborn as hell look that Congress is going to learn to fear.

"Don't ever say it, sir. You deserved our loyalty, our service and our pride. The MS didn't change who you were, even though I was angry enough to try to believe it had for a while. I went with Josh to see the Real Thing - and I found him."

You sit back in your chair, fold your arms and give me a look that dares me to disagree. It is my turn to wipe my eyes. I push the handkerchief back into my pocket and, reaching for my stick, stand up. Before you can rise, I put my hand on your shoulder.

'Senator Seaborn, you are going to make one hell of a president. I would be honoured to serve in your campaign in any way I can. All that I ask is that you be a better president than I was."

You stand up then and hug me.

"I can't," you say, a little raggedly.

As I hold you I whisper, "Just don't break your staff's hearts."