Disclaimer: I own neither 'Batman' or 'Castle', and the original idea for this story was inspired by a piece of fanart created by AwsomeGeek and is used with her permission

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War of the Daughters

Standing on the rooftops of Gotham, shivering in the cold- he'd brought what he could, but there was only so much that you could pack when going into a situation like this, and that was before you recognised the limits of what clothes could do for you when you lost so many other creature comforts-, Castle could only pray that this would work.

He'd been taking care of the phone as best he could, considering the circumstances, but that didn't mean that he could just ignore the human element of what he was about to try; it had been months since he'd spoken to either of the two people he was about to call, he had no real idea how they'd react to what he was about to ask them, he didn't even know if they were talking to each other right now…

But when the stakes were this high and this many lives were at risk, he had to try.

Besides, there was no way they'd be petty enough over how they'd left things last time to let an entire city get blown up because they were mad at him…

Dialling the number, Castle hit the 'call' button and waited for a few moments, praying for a positive response from this desperate effort, until the ringing ended with no sign that the call was to be rejected.

"Hello?" the familiar voice said at the other end of the line after a moment's pause.

"Esposito?" Castle said.

"Castle?" the detective replied, surprise in his voice more than anything else (Much to Castle's relief; considering how things had been the last time he and Esposito saw each other, he'd been anticipating needing to call him a few more times before Esposito deigned to listen to him). "What are you-?"

"Look, there's no time to explain everything, but you have to listen to me," Castle said hurriedly. "Kate and I are in Gotham City."

"I'm sorry; you're in Gotham?" Esposito said, incredulous anger in his voice at that news. "What the hell are you two doing-?"

"Like I said, that's a long story and this isn't the time to talk about that," Castle interrupted. "What is important is that the bomb Bane told everyone about in that announcement of his is going to go off tomorrow regardless of what anyone does to the city; Kate and I are working on getting everyone out of here, but there's only so much that we can do without outside help. We need you and Ryan to get to the main bridge and deal with the guards they've posted there before noon tomorrow; if we can get some of the people with potentially itchy trigger fingers out of the way on the outside, our back-up can work on evacuating the city."

"Uh… right," the detective said, sounding uncertain about the instruction even as he didn't seem to be explicitly rejecting Castle's instructions. "I… look, Castle, I get that this is serious- you'd never lie about something like that- but this isn't exactly-"

"If you're worried about the costs of getting here, I'll cover it," Castle said, quickly reeling off an account number and sort code to the cop; remembering numbers would be child's play for his old colleague (Were they at a point where they could be considered friends after how their last case went down?). "Get whatever you need from that and get the first plane ticket you can find; this all goes down tomorrow, and we need all hands on deck if we're going to get out of this."

"We'll be there," Esposito said, in the firm tone that made it clear he'd do whatever he could to respond to Castle's request.

"Thanks," Castle said. "We'll do what we can here, but…"

He trailed off, not wanting to even consider the possibility that he'd been about to voice, before he finished his sentence. "Just get here, OK?"

As he ended the call and began to hurry down the stairs towards the ground floor of the building, Castle could only hope that his message had been enough; the odds were already stacked against them to a point that it would be virtually impossible to make things worse, but the odds of them finding anything that would improve their chances were almost equally low…

Even as he hurried towards the manhole that had been identified as the most likely location for Blake to use to rescue the still-trapped cops, Castle didn't understand why he was doing this.

As much as he might like to act like one, he wasn't a professional cop, and most of his skills were amateurish at best; he might be able to match Beckett on the shooting range, but he was nowhere near her level in the field, and he wasn't exactly the master of kung-fu or anything like that…

But, on the other hand, if he'd just let this night go by with that phone call his one contribution to events, he'd spend the rest of the night feeling guilty and kicking himself. The rest of Kate's remaining forces- she might deny the responsibility, but with Gordon's pre-existing staff captured Kate was the one in charge of what was left- were busy trying to rally anyone who might have been remaining underground in other parts of the city to prepare for their last assault against Bane, but with his own assignment having required him to be somewhere else and his lack of knowledge of Gotham, he didn't have anything else to do but go for the guy most likely to need back-up.

As he drew closer, he slowed his progress along the streets to limit the possibility that he'd attract attention, taking his time and staying hidden in order to avoid anyone who might be looking or listening at the wrong moment, until he finally came up to a small drop in the ground which his old map of Gotham indicated had once been a road leading to a tunnel before Bane's strike against the city cut off the tunnel completely. Reaching one of the pillars surrounding the upper edge of the road, he immediately spotted Blake, kneeling on the ground in front of six men dressed in the dirty clothing of Bane's mercenaries, one of them pointing a pistol directly at Blake's head.

Castle was just about to try and give Blake a chance to escape by yelling at the men- maybe if they had something else to focus on Blake could take advantage of the distraction to do some damage-, but the plan was cut short before it could start when something tall and black dived down into the middle of the small circle of six, Blake exploiting the momentary distraction as his would-be executioner turned around to leap into action, grabbing the man's arm and hauling him forward as the new arrival almost effortlessly fended off the other five mercs. As the man in black knocked two of his opponents to the ground before kicking another in the chest before they could do anything but stare at him in shock, Castle virtually leapt over the side to join the fray, punching the kicked man in the face before he could get back up, leaving the black man to grapple with one of the men while Castle ran around the two fighters to go after the fifth man. His attention so focused on the new arrival, the other man didn't even notice Castle until the writer had kicked him between the legs, following the devastating blow up with a punch to the face that sent him to the ground.

It was only when he turned to look at the man in black after hearing something fall to the ground that he properly took in the distinctive points on his head and the long cape that hung behind him.

"Batman?" he said, grinning broadly at the sight of the man in back, only for his grin to falter when Batman turned to glare at him.

"Who are you?" the Dark Knight said, his voice low and gravelly as he glared at the other man.

"Uh… Richard Castle," the writer said, smiling awkwardly at the man who had prompted Kate to abandon New York to protect this city. "I'm… I came here with… Talia?"

"He's with us," Blake said, nodding in confirmation at Batman (Castle had never been more relieved that Gordon had trusted Blake enough to explain that particular kettle of fish to the guy; he might have wasted too much time explaining who Talia or Kate Beckett was otherwise, and the alias thing was something Kate should explain to this guy herself).

"Good," Batman said, looking at Castle with what he could have almost called a smile before he looked more firmly between them. "If you're going to do this regularly, you should wear a mask."

"We're not afraid to be seen standing up to these guys," Blake said firmly.

"The mask is not for you," Batman responded. "It's to protect the people you care about."

"Good call," Castle said, smiling slightly at Gotham's dark knight out of a lack of anything else to say. Not responding to Castle's comment, Batman reached into a container on his belt and pulled out what looked like a small ball with various silver protrusions on it, passing it on to Blake.

"Count to five then throw," Batman said, before he turned around and began to walk up the road. Glancing at Castle only to be met with equal confusion, Blake turned and threw the ball at the rubble, but only triggered a small explosion that made Castle think of a pop rather than the bang they'd been hoping for.

"Hey!" Blake said, turning to call after the now-vanished Batman. "No offence, but you got something bigger in that belt?"

As though in response to Blake's query, a massive object that reminded Castle of some of the images he'd seen of Batman's old car- it actually looked a bit like a bat when viewed from the right angle, with a cockpit and two turbines/weapons extending out from the front in a wing-like formation- flew up into position at the end of the road and fired at the rubble blocking the tunnel. With an exit now provided, it wasn't long until a group of men dressed in police uniforms began to emerge, hurrying out of the tunnels and back into the outside world they'd been cut off from for so long, exchanging brief words with Blake before Batman came back down the road to talk directly to the detective and Castle.

"What now?" Blake asked.

"All-out assault on Bane," Batman said grimly. "But you need to get people across the bridge."

"Why?" Blake asked.

"In case we fail," Castle said, his expression grim as he spoke for Batman and himself.

"Lead an exodus," Batman said, only pausing to nod in agreement of Castle's assessment before he continued speaking. "Save as many lives as you can."

"Talking of getting the non-combatants out," Castle put in, trying not to flinch as Batman turned to look at him- they might be on the same side, but that glare was very intimidating-, "I just made a call to a couple of friends from out of town; they'll do what they can to get to the bridge and ensure that nobody tries to stop anyone who tries to leave Gotham."

"You trust them?" Batman asked, looking pointedly at Castle.

"Talia and I have relied on them to have our backs for four years, and they never let us down," Castle replied firmly.

Batman simply nodded in response, but Castle decided to chalk that up as a positive confirmation of acceptance and focus on what actually mattered right now; he'd just received confirmation from Batman.

"You don't need me here?" Blake asked, reminding Castle to focus on the more immediate threat.

"You've given me an army," Batman replied. "Go."

"Thanks," Blake said, as he began to hurry up the road past Batman.

"Don't thank me yet," Batman replied.

"Well, I might not get a chance later," Blake said, before he continued to hurry along the road, leaving Castle to look at Batman.

"Hold on a minute," he said, as another thought occurred to him. "Commissioner Gordon was-!"

"Gordon and his men are safe," Batman said, looking grimly between them. "Bane and Miranda Tate are at City Hall; we're going to need to mount an offensive to keep his men occupied while Gordon goes after the bomb."

"Hence the need for the army, huh?" Castle said.

"Exactly," Batman said firmly. "I have a contact who might be able to give us another way out at the midtown tunnel; you need to make sure that these men all know the plan before we mount our offensive tomorrow."

"Understood," Castle said, nodding in grim understanding of the other man's solemn request.

Tomorrow morning, they were going to war with the man who'd arranged for the destruction of an entire city in the name of his lover's insane desire to fulfil what she perceived to be her father's dying wish, and their chances of success were questionable at best.

There was no other way to look at it; if they didn't commit everything to this fight, they were really screwed…

Which meant that there was a very real chance that some people wouldn't be coming back.

It wasn't like he wasn't aware of the risks- he'd been close to death more than a few times since he'd started following Kate around-, but there was still a difference between going into dangerous situations and a situation like the one they were about to face, where they knew that someone would die no matter what they tried to do…

But with the fate of the city at stake, Castle was just going to have to do what he did when disarming that dirty bomb; grab the cables and hope for the best.