Author's Note: I'm so sorry about the wait for this chapter. I was pretty devastated after one of the reviews for the previous chapter. But I know I need to accept feedback – whether positive or negative – if I am going to improve. And I do make a lot of changes based on your opinions. So thank you to each and every one of you who reviews, even the anonymous reviewer who almost made me cry.

This chapter is from Cap Montgomery's POV, and takes place during 3XK. I have borrowed some dialogue from that episode, which obviously I don't own.

Many years ago, in the Ancient, when the world began, was the war of the Gods. And there lived Atlas, who was known even amongst the great Titans for the great depth of his endurance. The Titans, oppressed by the Olympians, raged up against them. Atlas himself led the battle against Zeus for their freedom.

But after battling for ten long years, Zeus was victorious.

As punishment, Atlas was made the carry the weight of all the Heaven and the Earth upon his shoulders, and never rest.

Roy Montgomery knew how to bear a heavy burden. There were mountains upon his back.

Some days, Roy wondered why he even chose this job.

Even as a rookie, the guys at the precinct teased him. They said he is the job, and he'll never quit.

On the days when he was late to his wife's birthday dinner, or missed his eldest daughter's school play, he wanted to quit. Wanted to work in a bank somewhere, and put in his nine to five, and not have to wonder when he left the house in the morning if he'd still be in one piece that night.

He knew his job was a lot safer since his promotion to Captain, but being an officer in Manhattan was never safe, no matter what level.

Deep down he knew why he chose this job, and why he could never do anything else. He knew it every time he saw a victim's face, and remembered that that was someone's mother, or someone's brother, or someone's little girl.

So he kissed his wife every morning and went to work. And if some days clipping on that badge felt like adding a 50 pound weight, well that was ok.

Roy Montgomery was a strong man.

He could take it.

The day that Roy's nightmare came back started out like any other. He left the house before the girls were even up, planning to get some paperwork done. When the first vic rolled in, he didn't even realise.

Of course, his detectives were the best in the country for a reason. When Beckett came and told him that she believed the triple killer was back, he listened up.

God, he wanted her to be wrong.

But it was Beckett. Of course she wasn't.

Roy knew that if you work enough cases, you end up with a lot unsolved. It didn't make someone a bad cop. Over the years every detective ends up with cold cases. No matter how hard you work, how many leads you chase down, how many angles you work, some cases can't be solved. Roy knew that.

But be in the job for long enough, and you end up with A Case.

One case that burrows in under your skin and hooks itself deep inside.

It can be for almost any reason. Maybe you're the same age as the vic, or they go to your gym. Maybe the mode of the killing – drowning, fire, electrocution – hits on a particular fear you have. Maybe it's because you think you know the dirty sleezeball who did it, but you just can't get the evidence you need.

Whatever it is, it germinates inside your mind, flowering in the night as you lie awake, burrowing deeper, rooting itself, until you know every detail like you know your children's names.

Rachel Gold. Sara Townsend. Emma Keener.

Lauren Brackett. Sheri Ort. Melanie Sherman.

And now Linda Russo.

The triple killer. Roy had served on the initial task force that was created after the first murders, and the closest they had ever come to the killer was an FBI profile. Something about the way the triple killer placed the victims - so they looked like they were resting peacefully - had angered Roy. This man, this killer, had come into the homes of innocent women, brutally strangled them and ripped away the peace and happiness of six families, and then he had the audacity to pose them as though they were just sleeping.

It got to him.

It became his Case. The one that got away. The one that kept him up at night, long after he should have gone to bed.

For years he had been on tenterhooks, waiting for more murders. Convinced that every further woman that died at that man's hands was on Roy's fault. For not being smarter, quicker, more astute.

As the years had passed, the blind terror that this man would kill again had faded to the back of Roy's mind. But it had never gone away.

A man like the triple killer didn't just stop. Not after he had got a taste for killing. Roy had always known he would be back.

And now he was.

But the triple killer had made one great mistake.

Roy had deep faith in all of his detectives. They worked hard, they got results. But he had never seen anything like Kate Beckett. She would catch 3XK. It was only a matter of time.

Then Cal came back. Cal Townsend, the father of Sara, the second victim in the original killings. The reason why the triple killer had got under Roy's skin. Cal had been more than just another family member of a vic.

Roy had personally been the one to tell Cal that his daughter – his only child – was never coming home. Cal had looked at him, and in that moment, and Roy thought he could see into the man's very soul. The pain, the agony, that Roy saw there had stayed with him forever.

At that moment they hadn't been a Detective and a next of kin. They were just two fathers, confronted with the reality of having a child brutally ripped away, and Roy shivered with the knowledge that it could just as easily be him someday, being told that one of his girls was never coming home.

In that moment, Roy had vowed that he would catch the son of a bitch that killed Sara Townsend. But he never had. It was a failure that had claimed a piece of his soul.

Now years later, Cal was before him again, saying he had reporters coming around to his house, telling him that the triple killer was back. He asked Roy if it was true. And once again, Roy had to reassure the man that he was doing everything he could to catch his daughter's killer. And once again he had to see the pain, and disappointment in his eyes.

Just as he was leaving, Cal looked into his eyes, and begged him not to let it happen to another family.

Not to let it happen. Because even Cal knew that Roy had failed. And every new murder was on his conscience, because he let a guilty man get away.

Marcus Gates.

Roy rolled the name around in his mind. Marcus Gates. The triple killer.

Two days, and Beckett had managed to chase the guy to a bar in the Meatpacking District. He knew she was good.

Roy went personally to the take down. He wanted to look into the son of a bitch's eyes when they cornered him. Wanted to see the despair when he knew that he was caught.

But Marcus Gates laughed at him.

They took him back to the precinct. Roy watched Gates sit calmly in the interrogation room from behind the one-way mirror.

"Cold, implacable, the triple killer remains at ease, calm, in the lair of his enemy, with a resting heart rate of 50, set to match wits with his interrogators," said Castle beside him.

Roy glared at him.

"I just wanted to bring a literary flair to the moment, you know?" Castle continued.

Roy glared again. Sometimes he had no idea what Beckett saw in the man. Castle shut up.

The writer was spared from further harm but the arrival of Beckett entering through the door of the observation room, with the news that they had a warrant for Gates' apartment, which Ryan and Esposito were turning over as they spoke.

Roy knew that wasn't enough. They needed more than circumstantial evidence in this case. There was no way he was making the victim's families re-live all of this in court, only to have the case turned over, or the charges downgraded because of a lack of evidence.

Roy Montgomery was not going to let this man hurt another family, ever again.

Castle moved from beside him, headed to join Beckett in the interrogation room.

Roy reached out and laid a hand on the writer's forearm, stopping him. "Not this one, Castle," he said quietly.

This man strangled beautiful, defenceless women, probably due to some past trauma. The sight of Beckett, a powerful, intimidating, stunning woman, who held the power, and was not going to play by his rules, was going to mess with Gates. Roy didn't want anything messing that up.

The writer nodded, apparently aware of the gravity of this case, even if he had just tried to narrate the situation. They watched Beckett enter the interrogation room and take a seat.

Roy poised, tense, his entire being focused on the killer on the other side of the one-way mirror. If they had any chance at getting this guy to run off at the mouth and implicate himself, it was going to come from Beckett.

Every nerve in Roy's body was attuned to the moment, six years of pain and frustration resting on this moment. He felt Castle stiffen beside him, his gaze locked on the movement in the room before them.

But where Roy's whole attention was fixed on Gates' every breath, the writer's gaze was wholly focused on the detective sitting across from the triple killer.

Roy wasn't blind. He could see what was happening between the author and his best detective, probably better than they could. He imaged how the writer must feel, watching the woman he cared about locked in a room with a man who had murdered at least eight women. For a moment he almost felt bad about stopping the writer from going into the interrogation.

But this case was far more important than one man's feelings. And they were both aware that the detective could more than take care of herself.

Then Marcus Gates alibied out.

But it was him. Roy was sure of it. Now they knew who the guy was, they just had to get the evidence to prove it. They would build a solid case, Roy vowed. They would bring justice.

Watching Gates leave the precinct was a knife in the guts.

"Well, with this triple killer on the loose, you all better keep your loved ones close," said Gates as he left, a smirk never leaving his face. "Gosh, I hope you catch him."

Roy could almost see Beckett's blood boil as she watched him. Castle moved a step closer to her, whether to calm her down or in response to Gates' thinly veiled threat, Roy wasn't sure.

Enjoy the sunshine, Roy thought at Gates' departing back. Because we are going to build a case against you that is so strong, you'll never see fresh air again.

Roy watched as his team work extra hours, turning over every piece of evidence in the case, every possible lead.

Finally, they realised that their only real lead was Jerry Tyson, the cellmate of Marcus Gates.

At first, Tyson didn't want to talk, too afraid of reprisal attacks the prison if anyone found out he's a snitch. So they secured an early release from jail for Tyson, and then made sure he has protective police custody for him and his girlfriend.

Roy knew it would be worth it, once Tyson gave them the evidence they needed to finally build a case against Gates.

Tyson was able to give them all sorts of details that help build a case. But the one that finally clinched it was when Tyson told them that 3XK sometimes worked with a partner. From there they were able to track down his partner, a foster brother of Gates' from when he was a teenager. When they threatened to send his foster brother to prison, Gates finally cracked and confessed.

That night, Roy Montgomery had one of the highlights of his careers. He called Cal Townsend and invited him down to the precinct so the man could watch as Marcus Gates confessed to the murder of his daughter. Roy couldn't bring Sara back, but he could show Cal that they caught the demon who killed his daughter, and prove that he'll never be able to hurt another woman again.

After the interrogation he walked Cal to the elevator with a new sense of purpose, and something precious that he thought was gone; hope.

Once Cal had gone, Roy went back over to where Beckett was completing the formal arrest paperwork for Marcus Gates. "Great job, Detective."

"Thank you, Sir," she smiled back at him.

Roy couldn't shake the feeling that he was lighter somehow. As though he had been holding his breath for 6 years, and now he could exhale. "I think after a day like that, it's time to head home to my kids." He smiled unconsciously at the thought of their smiling faces.

"I think I'll do the same, Sir," replied Beckett. "I'm just waiting for Castle." Roy remembered that Castle and Ryan had gone down to pick up Jerry Tyson, and let him know that Gates had confessed. The detective glanced at her watch. "In fact, I would have thought they'd be back by now. I might just give him a call."

Roy nodded at the younger detective as she pulled out her cell phone and headed to his office to pack up his briefcase for the night. He had just finished, and was reaching for his jacket when Beckett burst into the room.

"Sir! We need to send a team to the safe house we had Jerry Tyson at. Castle and Ryan are in trouble."

"What? What did Castle say?" Roy asked urgently.

"It doesn't make sense. They should be back by now. I don't think Gates is the killer. I think Tyson is the 3XK and he set Gates up to take the fall in exchange for paying for his foster brother's heart surgery."

"Did you try calling Castle?" The detective nodded. "What did he say?"

"We don't have time…" Beckett hedged.

"Detective! I'll order a response team. But you have to tell me what he said that makes you think they're in danger. I need more than just a crazy theory."

"He said he loves me."

Roy froze. "What?" he asked, dumbfounded.

"You heard me," the detective replied, looking defiant despite the deep blush staining her cheeks.

"Yes I heard you. You want me to order a SWAT team because Richard Castle told you he loves you? Helen Keller could have figured that one out."

"It was how he said it."

Roy raised an eyebrow.

"Look, maybe he does feel –that – I mean – you know about me," Kate continued. Roy rolled his eyes at the level of the woman's denial. "But this is Richard Castle. If he was going to tell me he loved me he'd hire a sky writer, or have some dramatic confession in the park in the middle of a thunderstorm. He wouldn't just casually end a phone call with 'I love you' when he's never said it before. He was trying to tell me something, but someone was listening in on the conversation and that was the only way he could let me know something's wrong. I'm sure of it."

Roy waited, staring at the detective before him. Her agitation was obvious. She was actually terrified that something had happened to Castle and Ryan. And despite the fact that every officer in the building could see that Castle was in love with the detective, Roy Montgomery was a man who believed in his team and trusted their instincts.

So if Kate Beckett believed that Castle confessing his love was a sign of the apocalypse, he'd run with it.

"Go," he told the detective. "I'll get a team to meet you there, and I'll follow when I can." The words were barely out of his mouth before the detective was flying out the door and running to the stairs.

Roy made the call to send in a rapid response unit, and tried not to think of what he'd say to the commissioner if this was just Castle's way of making a move, and the team broke down the hotel door only to find the writer in a bed covered in rose petals.

Uniforms and Beckett had already swarmed the hotel by the time Roy arrived. The site of an ambulance parked in front of the hotel sent his heart racing. Beckett came over to him as soon as he stepped out of his vehicle.

"Tyson got away, Sir," she greeted him. "Castle's fine, the paramedics are just seeing Ryan. Tyson knocked him out, but he should be ok."

Roy felt his heart sink. Tyson really was 3XK. They had the wrong guy. He had hoped they were wrong, that there was some explanation for this that didn't end with the knowledge that the triple killer was still out there, ready to strike again.

He had failed.

Again.

And he would have to call Cal Townsend, and tell him that the man who killed his daughter was still free. He almost staggered backward as the weight of reality hit him.

Beckett gave him a sympathetic smile and touched his arm gently. "We'll catch him, Sir," she promised.

Roy could only nod, too burnt out to even speak.

Beckett walked off to make a phone call, leaving Roy to stand alone in the car park for a moment, watching the red and blue lights of the ambulance bounce of the glass windows.

He took a deep breath and made his way over to the other Ryan and Esposito, gathered at the back of the ambulance.

"Sir," greeted the detectives. Even the usually jovial Ryan was subdued.

"Glad to see you're alright, Detective," Roy replied.

"He got away, Sir," said Ryan, hanging his head. "If it hadn't been for Castle, I wouldn't have even realised we had the wrong guy."

"Don't beat yourself up about it, Detective. He had us all fooled."

The three of them stood in silence for a moment, staring up at the motel in the darkness.

"Esposito said you ordered everyone down here, Sir. But what I don't get is, how did you know to come here? How did you know that Tyson was the threat?" Ryan asked.

"Beckett phoned Castle to see where he was, and he told her he loved her. Beckett said she knew something had to be horribly wrong," said Roy dryly.

That a least got a smile from the two other detectives.

The three men stood in silence for a moment, until a uniform appeared to offer them coffee. Roy refused the beverage and walked away from the back of the ambulance, deep in thought.

He stopped suddenly at the fence surrounding the hotel pool and lent against it. In front of him, he watched the gentle ripples on the surface of the water and wanted to kick something.

He wanted to howl. He wanted someone to see the complete unfairness of the situation. He wanted to make things right.

He heard Beckett's voice again, and for a moment he thought the detective was talking to him. He turned, and spotted her taking a seat on a bench by the pool. Castle was sitting by her side, and Roy realised it was the writer she was talking to.

"Here you go," Beckett was saying, handing Castle a cup of coffee.

"Thanks," he said. He gestured to the phone in Beckett's hand. "Kids ok?" he asked, and Roy knew that must have been who Beckett was calling when she left him alone earlier.

"Martha said she can stay as late as we need."

"Thanks," said the writer. "Just a few more minutes. I don't want the kids to see me like this."

Beckett lent into his side. "Take as long as you need," she said softly. "There's just one thing I don't get. Why did he let you live?"

Castle looked at her in surprise, as though the answer was obvious. "To punish me. To make me pay for ruining his plan. Now he's going to kill again. All because I couldn't stop him. I failed. And I have to re-live that failure every day now." The writer closed his eyes. "I feel so guilty."

Maybe someone else would have tried to reassure the writer that it was not his fault. But Beckett carried mountains too. She knew the weight. She knew that no amount of logic could change that pain.

"I know the feeling," Beckett replied. Roy watched as she reached out and rested her hand on the writer's thigh.

"I know you do," Castle replied. He reached down and placed his right hand in her left, lacing their fingers together.

Roy watched them for a moment as they stared unseeingly into the distance, tucked in together, hands linked.

This is the reality of the job, Roy knew. The one that got away. The pain you have to carry. Responsibility. Guilt.

It was the burden that every officer knew. And now Richard Castle knew what it meant to bear the weight.

Now there were mountains upon his back, too.

But Richard Castle was a strong man.

He could take it.