A/N: Small edit to the last chapter. Rosemary was meant to be a few months older than Jack but a quick look at the wiki told me I'd mix up their birth year so I adjusted the date on her Missing Person poster

Let it never be said that Daniel Fitzgerald Reagan did not love his little sister. Sure they butt heads, sure he drove her crazy sometimes, but whether it was beating up bullies on the playground for her when they were kids or being there for her now that they were adults there was nothing Danny wouldn't do for her.

Because that's what big brothers were for.

Danny could still remember his grandpa sitting him down to explain it to him. "Being the oldest is a big responsibility," Pop had said. It was Danny's job to look out for his little siblings, keep them safe. Because that's what big brothers do.

"But," Pop added, "You gotta keep a special eye on your sister. Because girls are different; they're special. They need to be protected."

If Erin were to hear Pop say this now it was likely that she'd feel a little bit insulted. She could take care of herself just as well as any of the Reagan boys could, she didn't need protecting. And Danny knew that.

But Danny also knew that the world was different for Erin than it was for him. Women like Erin had to worry about walking home alone late at night or be following from a night out or some guy thinking they can do whatever they want. Women like Erin had to worry about the scum of the Earth who'd look at her and see an easy target.

Danny knew his little sister could look after herself. But it was his hope that she would never have to. So Danny took care of Erin's playground bullies, and when she got older he sat through Sleepless In Seattle and took care of boyfriends that made her cry. Because he was the big brother and that was his job.

But there was one time Danny couldn't keep his little sister safe and it ate him up inside. He could remember the day so well you'd think it happened yesterday and not over a decade ago:

It was a Saturday, just before lunch, when he got the call. His Sargent doesn't say much, and it makes Danny nervous. All Gormley says is that he needs to get down to Slope Park ASAP. He wasn't not prepared for the scene that meets his eyes.

There were more cop cars than there had any business being at a kid's park, and the first horrifying thought that crosses his mind is that there's been a shooting. But he knows that isn't right because for all the squad cars there are, there isn't a single ambulance.

Though he had no idea what was going on, Danny ran ahead with a sense of urgency, hoping to find someone in charge that could tell him what was going on, when something caught his eye. Or rather, someone. "Erin? Out of my way, I'm a cop, I'm a cop! Erin!"

He felt a bit like Moses trying to part the Red Sea, but eventually he was able to make his way over to his sister. She was crying and Danny was so stunned by this that he wasn't able to make heads or tails of what she was trying to tell him. "Erin, Erin what's going on?" Danny asked, trying to get his bearings, "What happened?"

"I-l can't find Rose! Someone's taken her Danny, someone's taken my baby!"

There were more tears and Danny had to hold Erin up to keep her from collapsing, all while feeling like someone had just knocked the wind out of him.

A lot happened at once then. Danny ran on autopilot, not letting his emotions go because he knew his sister was counting on him. His dad and Pop and Joe must know what's going on by now, so the first thing he does is call Erin's husband for her. There's so much going on she hasn't had a chance to call him herself yet, and Danny doesn't think she could hold a coherent conversation yet anyway.

Jack doesn't pick up and Danny leaves a scathing voicemail that says in no uncertain terms that his brother-in-law is to get his sorry ass over here as soon as possible.

He calls his mom next. There's a chance she knows already too, but he has to make sure someone's coming to sit with Erin. He calls but the house phone just rings and rings. It could mean mom's on her way already...or maybe she's just out and has no idea what's happening.

He debates it for a while but he decides not to call Linda. She'll rip him a new one for it later, but Danny decided it was for the best. Linda was pregnant, on bedrest and ready to pop, it seemed any day now. He wanted to keep his wife and unborn son safe at home.

With no idea just when the Reagan family cavalry would arrive, Danny takes charge. He made sure no less than three rookie cops are watching Nicky like a hawk and he takes Erin off a ways to sit on a bench with him and calm down.

It's like their roles are reversed, usually it's Erin who has to tell him to take a breather and Danny didn't feel like he was doing a very good job of it. He wished Joe were here, he was always better at that sort of thing. Instead Danny fell back on what he knew he was good at: police work.

He asked what happened. Who was around. If Erin saw anyone suspicious. Danny doesn't like what he hears. Not because it's bad but because there's just nothing there, nothing to work with, no lead to work off of.

Erin had taken her eyes off Rosemary for a minute or two tops. Nicky had gotten into some kind of an altercation with another kid on the playground and she'd sprung into action to separate the two. By the time she and the other kid's mother had gotten the two toddlers to apologize to each other and Erin had walked back to the bench, Rosie was gone. Erin hadn't seen anyone or anything suspicious. The park was full of little kids and their parents, no one looked out of place.

In those days Amber Alerts were new. So new in fact, they wouldn't become standard across the U.S for another three years. But even if that hadn't been the case there wasn't enough information for one anyway, with zero description of a potential abductor or the vehicle they might be using. Babies are so nondescript at that age that at a glance they all tend to look the same, so a description of Rosemary isn't much help either in the grand scheme of things.

It wasn't looking good, they were flying blind, but Danny didn't tell his sister this.

"I'll find her Erin, I swear I'll find her."

Dad shows up, then Joe, then Mom, and finally Jack.

Together the three Reagan men lead a perfectly textbook sweep of the area. The sea of uniforms fanned out and questioned passersby, they knocked on doors, they searched apartment buildings, they brought in dogs; but they found nothing.

No one saw anything, no one saw anyone, no one had the slightest clue where Rosemary was. It was like she'd vanished. But Danny knew that that was wrong. No one can just vanish, someone somewhere had to know something, so he carried on, all the while remembering the promises he'd made.

—

Danny was nothing if not a man of his word. But things take a turn when the canine unit finally finds something.

Rosie's blanket had been discovered in a back alley dumpster. They had to call Erin in to verify that it was hers. The blanket wasn't something common you'd find in a store, it was handmade. The name 'Rosemary' had been carefully stitched right on it, courtesy of Mary Reagan herself. Danny, Erin, Joe and Jamie had blankets just like it when they were babies. Nicky had one too and Jack would have one ready for him by the time he was born.

Danny wished they'd let him verify that the blanket was his niece's, if only to spare his sister the fresh wave of anguish that washed over her at the sight of it.

They find the blanket in the dumpster but they don't find a body. It was a hollow victory but a victory nonetheless and the Reagan family needed every bit of good news they could get, especially once they brought Erin in for questioning.

"You're a lawyer aren't you Mrs. Reagan-Boyle? That's a pretty stressful job. It can't have been easy, having to juggle your career, your little girl and a new baby. It's enough to drive anyone over the edge. Hell, I know my kids get on my nerves sometimes. I could understand if you lost control. Maybe Rosemary just wouldn't quiet down for you that morning and you got a little angry. Maybe there was an accident..."

"The thing is Mrs. Reagan, no one can tell us they physically saw your baby prior to her disappearance. You had her in her stroller and covered up by her blanket the whole time, why is that? It was a perfectly sunny day. A little vitamin D's good for babies isn't it….Could it be possible that Rosemary never actually made it to the park?"

Danny knew this was standard procedure. He knew that if the shoe was on the other foot he'd be the one asking these same questions, but that didn't stop him from being angry.

How dare they try and pin this on Erin. How dare they try and insinuate that his little sister would ever hurt her baby. It took every ounce of control he had not to burst into the interrogation room and pummel the detectives who couldn't have been more wrong. But Danny was stuck on the other side of the glass as they tore into Erin, they all were. None of the Reagan's were allowed on Rosemary's case, as family they were all too close to the situation; yet another standard procedure that would serve to haunt the family.

The most any of them could do was speak out on Erin's behalf to the detective in charge and corroborate what she'd said.

Yes, Erin's job was stressful but so were lots of people's jobs and they didn't do that sort of thing. She would never hurt her baby.

Yes, it was just as Erin said. Rosemary had just gotten over a cold. It made perfect sense that she'd want to keep her covered up. There was nothing suspicious about that.

"You're going after the wrong person. You're wasting time we don't have!"

Eventually they leave Erin alone but not before the relentless questioning leaves its mark on her. She'd already felt guilty about what'd happened but now those feelings had reached a whole other level. She scrutinized every decision she'd made that day, just as the detectives had done, agonizing over why she hadn't done this or that differently—why she hadn't noticed what was going on.

Danny had tried knocking some sense into her, they all had, but nothing could convince her. He didn't truly understand it until Jack was born.

There's a saying that says women become mothers the moment they find out they're pregnant, while a man becomes a father when he holds his baby. Danny thinks there must be some truth to this because, while he'd certainly loved his son beforehand, the moment he'd first held Jack in his arms had been indescribable. Danny didn't think he could ever love anything more. He'd never forgive himself if anything were to happen to his child, nevermind something like what'd happened to Rose.

"I'll find her Erin, I swear I'll find her."

Danny had meant those words, and he'd meant it when he'd promised Pop to look out for his sister. But despite his best efforts Danny had failed. He hadn't protected Erin, and thirteen years on he still hadn't found his niece. But one day he'd make things right.

A/N:

As a piece of additional information: Amber Alerts were started in honor of nine year old murder victim Amber Hagerman in 1996. The role out the program itself was slow and by 2001 only four states had Amber Alert systems in place. It wasn't until April 30, 2003, that President George W. Bush signed the PROTECT Act, which provided the tools necessary to create a national AMBER Alert program.