It starts on one of those rare evenings when they're both at home. Try as they might, their duty schedules clash more than they'd like, and this time spent together is precious.
They've opened a bottle of wine from the case Lily's parents gave them for their wedding, the fire is lit – it's a horrible, rainy night – and they're curled up on the sofa. They've learnt to be content with these little things.

Neither of them would be able to remember how the conversation gets on to holidays, but somehow it does, and they're reminiscing about childhood summers. James spent his in the South of France, in Switzerland, in Spain. Lily's holiday memories are of crowded campsites in Cornwall and Norfolk and -

"Wales!"

"Wales?" James repeats, wrinkling his nose. "I've never been."

"Oh, how can you have never been to Wales?" Lily exclaims. "It's brilliant!"

"Remus went once. He said it was just sheep and rain," says James. "How is that brilliant? You should have seen the place we stayed at in Nice …"

"All right, rich boy," Lily mutters, draining her glass and immediately pouring herself another. "All I'm saying is, you can't knock Wales 'til you've tried it. We used to stay at this place in –" her memory clouds over for a second, not helped by the wine – "Abersoch –"

"Bless you," says James.

"- shut up – and we'd drive out to other places for day trips. We climbed Snowdon once! I bet you've never climbed Snowdon."

"You're right," says James. "I haven't. Do you want a divorce now?"

"I'll let you off," Lily bargains, "if you agree you'll climb it at some point. We'll go, one day, and we'll stay in Abersoch –"

"Bless you."

"- sod off – and we'll climb Snowdon and it'll be really, really fun," she finishes decisively.

"If you insist," says James with an exaggerated sigh. "Does it have to be Wales, though?"

"Yes!" Lily cries, slapping her hand against the arm of the sofa. "Insult Wales and you insult me!"

"How does that work?"

"Well, I'm half-Welsh, aren't I?"

"Are you?" James looks at his wife disbelievingly. She smiles innocently back.

"Fine," he says, reaching for the wine. "Fine. We'll go to Wales. When the war's over." He glances up suddenly, struck with a thought. "This isn't our honeymoon, though, is it?"

"Oh no," Lily says comfortably, "perish the thought! We'll have our honeymoon in … I don't know … Italy. It must be somewhere abroad, I need to go abroad."

"You've never been abroad?" James shakes his head and decides to let that one go. "All right, Italy for the honeymoon. That has to be before Wales, though …"

"Why?"

"Because it's our honeymoon! First holiday as a married couple! It's got to be the first thing we do when all of this is over. Look, I'll write it down …"

Lily watches in amusement as he sets down his glass, grabs a piece of parchment and a quill from the coffee table and begins to write. A few moments later, he waves the parchment under her nose.

"'Things To Do When The War Is Over,'" she reads aloud.

1. Go on the honeymoon (Italy)
2. Go to Wales

And so it begins. The list is pinned to the kitchen wall, and over time steadily grows longer and longer. Some are small things, like

8. Have a picnic in the park (and find a nice park)

and

15. Have a barbecue

but there are long-term plans, too, such as

20. Buy a house in France

and

26. Move to the seaside.

It becomes a way of keeping their spirits up when things are looking especially bleak; a beacon of hope for the future. It remains that until

22. Have children

is changed, on a dark Sunday afternoon in December, to

22. Have more children.

Lily stares at the words, the quill trembling in her hand. She doesn't quite know why she did it. She isn't really thinking straight.
They're making this list of things to do when the war is over because they can't focus on anything but the war right now. It's all-consuming, they never know when they're going to be called out, it's terrifying and dangerous and dark, and she's bringing a child into that.
This isn't right! Have children is on that list for a reason, because it's way in the future, barely visible at this point. They're not ready. She's nineteen! If she were in the Muggle world she'd probably be at university right now, still a student, not even thinking about settling down, but instead she's in the middle of a war, married and pregnant.
Pregnant. Oh God. And there'll be a baby. A real human, needing constant care and attention and love –

She feels something pressing into her stomach, and, with a jolt, realises her hand has crept down to rest against a non-existent bump. Feeling sick, she curls both arms tightly around her body, slides to the floor and cries.

The list seems to be staring at them.

They've been sitting in silence for some time. Hours, perhaps. The drip of the tap is the only sound.
Ever since Dumbledore left, his words have been running through their minds again and again. The one with the power to vanquish the Dark Lord.

Neither can live while the other survives.

James glances at the list again. There's the title, written by him so long ago, clearly underlined in black ink.

Things To Do When The War Is Over.

Their child – or son, if the prophecy did indeed apply to them – son, they were having a boy? He'd have a son! – could ensure the end of the war. He and Lily both knew why they'd persisted with that list; part hope, part delusion, because both of them often thought that the war might not ever be over. But now …

"It could happen," Lily says hoarsely. Her eyes, too, are fixed on the list.

"It could happen."

Harry is everything they never knew they wanted. He makes them laugh and cry and fall in love for the second time. The list becomes dominated by his name.

41. Take Harry to his first Quidditch match
43. Take Harry to meet Father Christmas
45. Go on Harry's first holiday

There's some debate over whether or not Harry's first holiday will in fact be their honeymoon, but eventually they agree that the honeymoon will come first, and Harry can stay with Sirius.

They're hopeful again. He's their child, and they love him, and when they're with him they can close their eyes and try to forget that one of their friends might be working against them, and that they're in hiding, and that years have passed since they began that list and they don't know how close they are to ticking anything off.

When the Fidelius Charm is cast, they have one of the happiest nights any of them can remember, adding more and more entries to the list and sipping wine and laughing and playfully arguing about where they'll go on the many holidays they have planned. They're protected now; only Peter can tell of their whereabouts, and as Sirius put it, "no one would go running to Peter for a secret!"

A week later, the war is over, but they'll never cross anything off the list.