They picked Luna up from the Hogwarts Express themselves, and brought her to stay in the spare bedroom above their shop.
The Weasleys celebrated Christmas, but Delphi had introduced the twins to Yule, and in her memory they lit a Yule log with Luna and went through that tradition with mixed humour and solemnity, but an authenticity that could not follow them to the Burrow on the 25th.
Luna refused to come with them, heading instead to the Longbottom household for the day. They were perfectly prepared to do the shovel talk with Neville if necessary, but didn't want to deprive Delphi of the pleasure when they got her back.
She did have quite the way with judgemental matriarchs too.

Anyway, Christmas with their wonderful, loud and almost universally tactless family.
It was filled with as many poorly thought out comments, awkward pauses and sideways glances as they'd expected. Worse than they expected was their mother having the audacity to make a comment filled with suggestion about how involved Angela and Katie were becoming at their shop.
It was really bad.

The gifts were much better.
Bill and Fleur gave them a picture of them at the cottage, laughing sat on the beach, Delphi between them head on Fred's shoulder. The frame was silver, worked to look like ferns wafting in the breeze. Charlie got them purple and orange throw blankets that were weighted and warm, treated with a modified love potion to smell of...well, to them, Delphi.
That caused Fred to break down, George had to thank Charlie for both of them while his twin spent some time outside.
Their father and Percy joined the ranks of considerate gift givers, both working together to give the pair a membership for delivery of cooked dinners three times a week.
Ginny and Harry got them purple scarves, just the right shade.
Ron and Hermione gave them a rowan/mountain ash bonsai which was definitely Hermione's idea.
Their mother gave them jumpers, though much like Ginny, her's were in purple wool.

Despite the gifts that made them feel much more charitable as a whole, they decided to leave early. The others wouldn't really let themselves have fun until Fred and George weren't around looking years older than they actually were and producing an aura of misery despite their impressive bravado.

Surprisingly, Ron walked them to the door.

Ron and Hermione had been going steady since the battle, and getting on far better than even anyone expected, least of all the couple themselves. The war had matured Ron a great deal, and mellowed Hermione enough that their bickering rarely escalated.
Ginny and Harry were another matter, the golden boy being a lot more scarred and damaged by all that had happened, he'd even considered leaving the Wizarding world altogether at one point. Ginny had to coax him and handle him like a rescue animal, not that they could blame the guy at all.

Ron shuffled awkwardly in the hallway, moving foot to foot.
"You guys...aren't doing okay." He'd stated eventually.
"Blimey Gred," commented Fred sarcastically, "Ronnie-kin's insight knows no bounds!"
Ron glowered. "Quit it. I'm trying to say something meaningful."
George poked his head out the door to check the sky, "sky ain't falling Forge."
Ron groaned before thrusting his closed hand toward them, "here. You gits. Take it."
George raised an eyebrow but did just that, opening his palm to find a familiar lighter.
"Dumbledore's Deluminator?"
Ron smiled distantly, "It does more than turn lights on and off. Helped me find Hermione actually...after....after I left. Maybe it'll help you guys too. 'Mione says if I use it one more time in the dorms she'll dump me anyways."

George let his fingers close around the device hesitantly, even though he had no idea how it was supposed to help them in any way. It was Dumbledore's, if it turned out not to help, they could stomp on it for stress relief.
And yes, the man was dead, did not mean he wasn't an underaged girl mind rapist. Git.
"Thanks." Said Fred.
The three shared an awkward nod, before Ron turned away and headed toward the kitchen, no doubt after some more sausage rolls.

———

The only hint they'd managed to gather from Xenophilous was that they weren't the only ones to ask him, Harry had. The boy himself they'd known was already aware, through his talk with Voldemort during the battle. It was unclear however, if that was purely about the elder wand or not, and either way Luna had warned them against discussing their true goals with the Boy who Lived. Her warning made them very reluctant to approach Harry at all.
Not when they only had one hallow to show for their efforts, and the boy in question was a few poor sentences off a mental break down at the moment.

That meant, as they walked up to their shop in diagon, the night of the 25th of December, they had no leads on the resurrection stone, and were, like many bereaved, feeling their loss more sharply for the time of year.

It was why, in some vain attempt to spark some enthusiasm or curiosity, George pulled out the deluminator from his trouser pocket, as they sat in silence in the living room. He clicked and watched dispassionately as the light in the lamp on the mantle flew into the device in his hands.
It roused nothing in him, and though he couldn't see Fred's own expression in the darkness, he knew his brother hadn't even twitched.

What a pathetic gimmick.
If Dumbledore was so clever he'd have made an expandable magic carpet to prevent him getting killed due to falling from great heights.

He clicked the thing again to get the lamp light back but though the light re-emerged, it didn't return to the lamp, hovering between them and illuminating Fred's irate expression.
"Of course the moment we use it, it bloody breaks." Growled his brother, but a faint sound had George raising his hand for silence.

At first he was sure someone had gotten through the wards, and the faint voice was coming from below.

Then the intonations of the...what must be singing, pinged somewhere in his brain as familiar.
Just as he grasped that the sound was coming from the ball of light, it moved away from him and he and Fred both scrambled from their chairs to follow, minds racing.

"...as down the glen one Easter morn,
To a fair city rode I.
There armed lines of marching men,
In squadrons passed me by..."

George knocked over an entire shelf of fake wands in his scramble to follow the light out of their shop onto the main street. The voice was loud enough that he could just make out the words, but still faint enough that he'd rather assume that his mind was playing tricks on him than believe that the singer was Delphi.

"...no battle drum did sound it's loud tattoo.
But the Angelus Bells o'er the Liffey swells,
Rang out in the foggy dew..."

The shops of Diagon Alley were dark, though many lights were on in the floors above. It was snowing now but neither George nor Fred had bothered to take off their coats on their return to begin with. A small part of his mind was thankful for that, but most of George was straining to catch every word even though the ball remained just out of reach.

"...Right proudly high in Dublin town,
Hung they a flag of war,
'Twas better to die 'neath that Irish sky,
Than at Sulva or Sud-El-Bar..."

The pub was locked up for the night, but apparently they only needed to get out of the alley's apparition wards, as here the orb halted.

"...and from the plains of Royal Meath..."

It then split in two and shot into their chests, and suddenly George knew where to apparate to. He did just that, Fred a moment faster.
They found themselves outside the gates of Hogwarts. There was a tense moment where neither knew what to do, before the orbs left their chests and reunited.

"...with their long range guns,
Sailed through the foggy dew..."

The orb floated toward the gates which opened for it immediately allowing the twins through, before the light floated off the path into the forbidden forest. George knew they should be getting concerned, with a variety of things, but he did not have it in him to care.

"...the requiem bell...for those who died..."

George face planted into the undergrowth twice as they hurried deeper into the woods, thankfully Fred never tripped the same time he did or they would have lost sight of the orb which raced before them, seeming to be much fainter and smaller then when they had started out.
If it was hurrying to try and get them somewhere before it ran out of energy there was little more George could do to speed up his pursuit, he was certain the roots were deliberately moving to catch their feet, and he wouldn't be surprised from his experiences.
The forbidden forest was not an evil place, truly it wasn't, but it held no affection for most wixen, much like the sentient creatures it protected within.

"...While the world did gaze...those fearless men..."

They themselves had probably earned its personal dislike in the past, regret for that useless at this point as he desperately chased the fading voice of the woman he loved.

"My heart with grief was sore...for I parted then with the valiant men..."

Fred gave a yelp of actual pain and George turned to see him scrambling to his feet, weight firmly favouring his right foot.
They only met eyes long enough for George to confirm the injury wasn't dire before he was turning back to the chase.

"...whom I never shall see n'more..."

The orb had started out the size of two fists together, now it was smaller than a snitch, and he could barely catch the words echoing from it as the shadows around them gained strength and frost in the air chilled George's lungs.

"...when you fell..."

The orb was gobstone sized, the voice barely a breath in the frigid air.
"No..." whispered Fred as the light sputtered, it's flight listing to the side like a damaged aircraft.

"...the foggy dew..."

The light abruptly flickered out, leaving Fred and George bloody and bleeding in the pitch black forbidden forest.

At least it couldn't-

Something cold and sharp was suddenly pressed against his back, and George was regretting so many life choices.

———

The song is 'The foggy dew', an Irish classic, though kind of randomly chosen as I couldn't find one with a good balance of longing and hopefulness that wasn't about alcohol.