Disclaimer: I don't own Person of Interest - I'm just borrowing the characters and not gaining any money.

Author's notes: In Greek mythology Acheron, the river of sorrow, was one of the five rivers of Hades.

Acknowledgments: Thank you, scully1138, for practically dropping everything to proof-read this. Like I said ... the best.

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"You couldn't save your friend. But you could have if you had known in time. And that's the other thing I'm offering you. A chance to be there in time."

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Harold remembered that moment like it had been yesterday. The moment he had promised John Reese the chance to be there in time - to stop bad things from happening.

John had been more than lost when Harold found him and Finch had seen it in the other man's eyes - the small spark of hope for redemption - when he offered him that promise. To be there in time.

And they had saved lives. For two years they both had voluntarily put their lives on the line in order to save literal strangers - John more so than Harold. That fact alone would have made pretty much anyone else reconsider their involvement with the Machine and most likely tell Finch where he could shove his money right after the first mission to save a number. But not John Reese.

John had liked the job ... purpose - or whatever you wanted to call it. He had admitted that much himself. And Finch had to concede that he liked having the former ex-op around - that without him there most likely wouldn't have been any lives saved at all.

That's what they did. They saved lives.

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"Not all of them."

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But everything had changed now. He hadn't been able to keep his promise. They had not been in time when it had mattered the most. When the number had not been just some unknown face but one of their own. And Harold knew that ultimately it had been his fault.

There were so many reasons why Harold had come to that conclusion. He could have listened to Ms. Shaw when she had suggested asking Root for help or at least accepted the latter's help when she had voluntarily offered it. But he had refused - his declination born out of a deep mistrust and even fear of the woman. That - Harold was sure - John would have understood. However, Harold had - a long time ago - chosen not to have any direct communication with the Machine like Root had, even though he could have had that kind of access ever since the Machine had been set free. But he hadn't wanted that - afraid of what he might become if he had that kind of power. And Root had confirmed it - the Machine respected his wishes.

But if he had just allowed the Machine to contact him directly, to forgo the public telephones and the Dewey Decimal encoding, they would have been warned. There would have been time to save Joss Carter.

But instead he had stood frozen to the spot and watched helplessly as they lost more than a mere ally or moral compass. No, they had lost something that he had learned was far more valuable and a lot harder to come by in their chosen line of profession than either of those two things. He'd watched a friend die in the arms of John Reese.

On some level Harold Finch hadn't really been surprised when he had discovered John's sickbed empty one day with no sign of the ex-op to be found. After all, he had failed John just as much as he had failed Joss Carter. Only John was still alive - because Harold eventually had asked the Machine for help to save a life that in John Reese's eyes had never been worth saving.

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We got into this to stop bad things from happening to good people. Carter's been doing that her whole life. She's not just another number, Finch. Some people the world can't afford to lose.

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Harold understood why John needed distance. From the Machine. And from him.

However, he couldn't shake the feeling that Mr. Reese had no intention of ever coming back and he doubted that Detective Fusco's well-meaning efforts of convincing John otherwise were going to make any difference.

The Detective had been incredulous at Finch's quiet acceptance of Reese's leaving, insisting that they should go after him. Finch knew with a painful clarity that he would not just miss the help of Mr. Reese - his employee in that venture of his - but even more so the quiet companionship of John, his friend. But what would he say to John when they found him? That he was sorry and please come back to risk your life for total strangers again?

After John had left Harold realized that he couldn't stand the formerly comforting silence at the Library with all its reminders of his failure. If it weren't for his obligations to take care of Ms. Groves, he would probably give it a wide berth all together for the time being - though, he still found himself aimlessly wandering the streets with Bear – his thoughts a million miles away.

Finch stopped at a sound that – ever since that fateful night - he knew would be haunting him for the rest of his life. He stared at the ringing pay phone and realized that he didn't know if he still could do it – if he still wanted to do it. He had started trying to save the numbers on the Irrelevant list in the wake of Nathan's death, so that his friend hadn't died in vain. At least that's what he had told himself. But ultimately Harold had to admit that his reasons had been far more egotistical. He'd wanted to redeem himself.

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You would have to face a very painful truth. That you are not God. You don't control who lives or dies.

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He had thought that with the Machine he would actually stand a chance. However, now he wasn't so sure that the price others had paid for his attempts of making amends had been worth it.

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Does survivor's guilt pass when everything that has happened actually is in fact your fault?

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And for the first time Harold Finch turned away and let it ring.