She's read that, unlike in the Wizarding world where a person comes of age at seventeen, in the Muggle world it varies, although for most purposes in the UK it’s eighteen. Either way, Luna has already been considered an adult by most societies for some time, even if she's not always treated as such. Turning twenty-one still seems to be a special occasion in the Lovegood household.
Daddy tells her that it's time for her to receive 'the key to the door'. She assumes that this means the key to their home, which according to Muggle tradition is symbolic of her becoming a kind of 'senior' member of the family. A proper adult and not just a young adult.
(She's also receiving her own desk in the newly purchased offices for The Quibbler, a jar of Practagoria scales, a copy of the latest new edition of Fantastic Beasts and Where To Find Them, her mother's wedding ring, and the recipe for the best scrambled eggs and banana concoction ever invented.)
Luna likes to think that she is an open-minded individual who does not form assumptions. A key to a door could be any key to any door. She wonders what a key made just for her would look like and what lock it what fit.
The important thing though is that keys make doors open.
Zoë turns twenty-one on a battlefield. She's a career soldier, fighting since she was old enough to enlist, and before that fighting for the right to when her large, nomadic family refused to let her put her life on the line for territory, for dirt and earth. Always fighting. This is just another day of it. It’s a milestone though, becoming another year older. Another year survived.
The rattle of gunfire sounds to her right and she hunkers down in the trench until it stops, before peering up out of the glorified hole dug in the mud and over the shallow mound of sandbags that line the edge. The uniformed bodies to either side of her stay down and she doesn't blame them. It's all too easy to confuse what's safe with what's right.
She wonders if they count their years. The months, the weeks, the days. The minutes. Do they count winning as the end of the next battle or having survived it?
She raises her riffle, the last weapon she has left, as a figure comes racing towards her, and then lowers it slightly as she recognises that the brown of his uniform is the actual colour and not just a mud covering. He's splattered with plenty of that too, their new Sergeant Reynolds, transferred from the 34th or the 75th or whichever battalion managed to lose only half their troops at Craigsdown. She hasn't seen him for sometime today and had thought they'd lost yet another over-eager officer, but here he comes, grenade in one hand and pin in the other. He tosses it back over his shoulder with a yell and keeps on coming.
"You know what'd be a real nice present right now?" he says, just moments after launching himself into the trench next to her. "Zoë, right? What I'd really like, Zoë, would be some more of those grenades. You have any of those?"
"That would a no," she tells him, keeping her eyes and riffle focussed on the battlefield. "Sir."
"Now that's a pity and a shame." Zoë can hear him shifting around next to her and see him out of the corner of her eye, trying to wipe the worst of the mud off his face with an equally muddy coat sleeve. "How 'bout some soap?"
He's informal and somewhat amusing, and he comes to crouch next to her rather than hiding at the bottom of their pit. She thinks she might come to like this one. Maybe.
"Seeing how it's my birthday today, sir, I think it should be you giving me a present actually."
Reynolds laughs and his hand comes into her field of vision to slip a grenade pin into her coat pocket.
Some people, she thinks, probably don't count at all.
Okay, so he's still wearing the black leather jacket, but Rose has never seen the Doctor in a suit and tie before. Black trousers, black shirt, black tie with a silver TARDIS tie pin. He's still the Doctor though, a goofy grin on his face as he aims his sonic screwdriver at something purple and square-ish on the ship's console.
"Hey," she says, resting her elbows on a railing and letting her hands dangle. "You didn't tell me it was a special non-jeans wearing day. What’s the occasion?"
"My birthday! Twenty-one today."
He prods the purple thing and it hums happily. She guesses that means he's fixed whatever it was that needed fixing. Unless broken parts of the TARDIS are meant to sound happy.
"Hang on. I thought you said you were nine hundred or something?"
"Well, yes. I am." He pockets the sonic screwdriver and leans forward to adjust a monitor. "But I'm also twenty-one. This time around."
"Oh! I get it." She grabs hold of the railing and leans backwards until holding onto it is the only thing stopping her from falling. "You're always twenty-one, right? Every year, when anyone asks. Mum was like that 'till I told her I wasn't that bad at maths."
"Not really, no. It's more something that happens to me. Every so often. I'm twenty-one in this body."
Rose pulls herself upright and walks over to stand next to the Doctor, so she can see what's so interesting about the monitor that he can't seem to look away from.
"What? So you're some kind of body-snatching alien? Should I be worried?" She nudges him in the side with her elbow. "Or don't you go for girls?"
"Cake." He turns to smile at her, wide and happy. "We should have cake. It's traditional. And I know the perfect place. With really great cake."
"Let me guess. Banana flavoured, right?" Rose lets him steer the conversation wherever he likes, nudges him again with her elbow, and grins. "How many candles are we putting on it, then?"
He celebrates every century, would celebrate every year too if he could remember the date. He likes celebrating. Twenty-one is a special number though, like eighteen, thirty, seventy-five. It just is. Might not be anymore in whatever passes for society or culture these days, but when it comes to what he thinks about birthdays, it just is.
"Twenty-first century to twenty-one centuries," he says out loud in the empty workshop. "Bugger, I'm old."
"Living forever means being old for a long time."
Spike glares at the legless robot he's trying to complete. The head is already finished. He likes something to talk to whilst he's working.
"You're not meant to be a philosopher, love."
"I think old people are sexy."
He pats her on the arm and starts grafting what will be a thigh muscle onto the nervous system wiring. It's about two hours later and he's just finishing the second calf when Xander strolls in.
"Y'know, you and robots? Kind of creepy."
"Only 'kind of'?" Spike seals the last connector before turning to face him. "Must be losing my touch."
"There is no such thing as inappropriate touching," says the robot. It’s nearly done, but there's no kind of skin covering yet, just the inner workings. It wriggles forward to the edge of the work bench and flexes its new muscles.
"I still can't get over how many of those you sell, and for how much money," says Xander, shaking his head. "Seriously."
"Pays the bills, so sod off," says Spike. Not that he wants the only non-robot person he knows, really knows, to leave.
He'd always thought it'd be one of the others still around this long after. Someone with magic, or Angel, who Spike has never been able to get rid of and not for lack of trying. Hell, he never though that he himself would be around this long, soul or no soul, let alone one-eyed, still completely human Xander. For a given value of human, since Spike maintains there's got to be some reason he hasn't grown old and kicked the bucket.
"Found another Slayer today."
"They're everywhere," says Spike, "so it's not like that's difficult, is it?"
Except when it is, but this time it doesn't look like it was.
Twenty-one centuries and Xander is still looking for Slayers, explaining what it means to be them, initiating them into a whole new world of hurt. He thinks it's why he's still around, that maybe The Powers That Be, or whoever the higher-ups are who make that kind of decision, need him to keep on doing what he's doing.
Spike, though. Spike thinks maybe Xander is here to keep him doing what he's doing, to keep him holding onto his soul.
It's as good a reason as any.
"I come bearing a birthday present," says Xander. "Also, tasty liquids."
"Better. Now bloody well bring it over here."