Three months later, Albus Dumbledore arrived on the Potters' doorstep with a message: Voldemort had eyes on their newborn son, and a target had been placed on the entire family. If they didn't go into hiding immediately, they'd all be dead within the week.

James cornered Dumbledore as he tried to leave, and demanded an explanation.

"I am afraid, Mr. Potter, that there is little else I can say. Voldemort has become convinced that your Harry is the child referred to by the prophecy. The truth of it does not matter to him. As far as he is concerned, all he has done will have been in vain as long as the child continues to live."

"So, that's it then?" James asked, frustrated, "We're just expected to go into hiding indefinitely? There's nothing we can do to fight this, to stop him? Come on, Professor, don't tell me you don't have any of his people under your thumb. Isn't there anything we could do, anyone we could go to? This is my son we're talking about, my family!"

Dumbledore shot him a surprisingly cold look, and James was taken aback.

"At present," he said, "I am afraid this is the only option. We can only hope that soon enough the war will be won, or, perhaps, a more favourable solution will present itself."

Dumbledore's expression softened and he placed a grandfatherly hand on James's shoulder. "I understand how difficult this must be for you," he said, "but you must trust that I will do everything in my power to safeguard your family. For now, the most important thing you can do is cast a Fidelius Charm. As long as that holds, you and your family will be safe. Are you sure you do not want me to act as secret-keeper?"

"Thank you, Professor, but yes."

"Very well."

While they were talking, Rosemary had snuck up on her father and grabbed onto one of his trouser pockets. Dumbledore glanced down at the little girl, whose toddler face was now covered in a smattering of freckles, and who looked up at him with her dark, round eyes. He smiled at her gently and squeezed James' shoulder. And with a simple goodbye, he was gone.

James closed the door and dragged his hand across his face. Rosemary tried to reach her hand into her father's pocket and grab something, but was quickly pulled away.

"Nice try," James said. "But no taking things, remember? You have to ask."

Rosemary gave a frustrated grunt. "Ca' a hab won?" She asked, her fat little fist grabbing the air.

"'Can I have your wand, please,'" James told her.

"Ca' a hab won pees?" the little girl repeated.

James took his wand out of his pocket and handed it to Rosemary, who shrieked with glee as sparks flew out of the end and ran off into the living room.

"What do you say, Rosie?" James called out to her.

"Tank oo!" came the response, followed by a faint popping sound as the toddler proceeded to poke her father's wand at the little collection of pebbles and snail shells that she'd carried home in her pockets from the park.

James smiled wistfully at her happy ignorance of the danger they were in.

At the same time, Lily came downstairs with Harry, who had woken up from his nap during Dumbledore's visit. She looked at James with eyes full of concern, wondering if Dumbledore had said anything else.

Understanding the unspoken question, James shook his head.

"We need to cast the charm tonight, James," Lily said.

"I know," he said, "I'm going to contact Sirius."

Lily nodded. They had already discussed using Sirius as their secret-keeper while Dumbledore was with them. "I'll start getting ready to cast the spell," she said. "It will take a while. I haven't done anything this complicated before. I'm not actually completely sure that I can pull it off."

James smiled at her gently. "Well, if anyone can cast an immensely complex and difficult charm that could be the only thing between life and death for our entire family, it's the witch who earned the highest recorded score in twenty years on her Charms NEWT."

"Oh God," Lily groaned.

"You'll be fine," James assured her. "Now let's just hope that Sirius has that mirror on him."

...

Though he would never tell James, Sirius always carried his two-way mirror on him, even when he was spending the evening mooching around the London underbelly and hitting on every scantily-dressed woman that walked by. He was on the Potters' doorstep within two minutes of James contacting him.

Lily opened the door and hugged him, but pulled back suddenly with a disgusted gag.

"Where have you been?" she asked. "You smell awful!"

"Oh, it's just the natural eau de chien, Lilypop," said Sirius, who had been spending a lot of time in his animagus form, and found himself frequently giving in to the instinct to get up-close-and-personal with just about everything that gave off a potent odor.

Lily frowned at him. "Well, I'm glad you're here," she said, "even if you do smell like a dying animal."

"How's Prongs?" Sirius asked. "He didn't sound good."

"He's not. Neither of us are. But he's in the kitchen with the kids if you want to come on inside."

Sirius followed Lily into the kitchen and laughed as Rosemary gave a cry of delight at his appearance.

"Where's my favorite should-have-been goddaughter?" he called out.

"Oh, not this again," said James, giving his best friend a one-armed hug.

Rosemary bounced up and down in her high chair. "Pafoo! Pafoo!"

Sirius rumpled her dark-red curls. "You both know that I should have been her godfather," he said.

Lily sighed. "Well, at the time we thought that Remus was the more responsible one."

Sirius snorted. "Moony, God love him, is a walking existential crisis," he said. "But at least I get Harry, and Rosie here can be my honorary goddaughter, can't you?"

Rosemary giggled. Sirius shot her a grin and then turned back to face James and Lily.

"So what happened?" He asked. "What's wrong?"

"He's after Harry," James said, matter-of-factly.

"What? Who's after Harry?" Sirius asked, looking at the tiny baby asleep in a rocker by the doorway.

"Voldemort."

Sirius paled. "I don't understand," he said. "Why the hell is Voldemort interested in a baby?"

"Apparently there's some kind of prophecy about a child born at the end of July to parents who've pissed him off, what? Three times? Anyway, Voldemort learned about it and he thinks that it refers to Harry."

"But that's ridiculous, he's only a few months old. He can't even sit up yet. Rosie could probably hurt him more than Harry could!"

"Yeah, she probably could," said James with an angry sigh, "but it doesn't matter, because Voldemort is paranoid, and our three-month-old son is his new biggest threat."

"Shit," said Sirius. "What are you going to do? Have you spoken to Dumbledore? The Order? Please tell me they have a plan."

"Yeah," James said, "Dumbledore wants us to go into hiding. We need to put a Fidelius charm on the house. We were hoping that you would act as secret-keeper."

Sirius was silent for a moment. "Don't use me," he said finally, "use Wormtail."

"What?" Lily exclaimed, "Why?"

"Two reasons," Sirius said, "The biggest being that anyone who knows you will know that you'll have asked me. You can use that to throw Voldemort off the scent. No one will suspect Wormtail because everyone knows that he's, well, Wormtail. Trust me on this, you don't want to go with the obvious choice. But also, you both know that most of my family are death-eaters."

Sirius scowled as he said the last word. "I could become a liability, and I wouldn't be able to live with myself if anything happened to you because of me."

"So you want us to use Peter as our secret-keeper?" asked Lily, incredulously.

"It's the smart choice," said Sirius.

Lily and James glanced at each other, before James sighed and reluctantly agreed.

"Fine," he said, "we'll use Wormtail. But you'd better have a way of getting hold of him, Padfoot, because we need to do this tonight."

"I do," said Sirius. "I'll make sure he gets his furry little ass here within an hour."

James nodded. "I hope you're right about this," he said.

Sirius met his gaze. "I am," he said.

...

Peter Pettigrew showed up sixty-seven minutes later, looking vaguely disheveled but otherwise in high spirits. He was pleased to be needed, and excited to be entrusted with such a serious role. Lily and James's hesitation abated as they saw his eagerness, and with a short exchange of words, all was agreed upon.

That night, as the children slept, a bright golden light emanated from the Potters' living room, and as Peter took the oath of secret keeper, the small tudor house vanished from sight.