(Author Notes expanded: Sunday, November 6th, 2016)
Disclaimer: I am not J.K. Rowling. I do not own Harry Potter.
Note: The following piece is set in an Alternate Universe, where Luna Lovegood was born a generation earlier. I'm not clear on the canon dates of birth for members of the Lovegood family, but as far as this story goes, I assumed that Xenophilius Lovegood is Luna's older brother, and a dozen years her senior. Their parents are both deceased by the summer of 1976, when this short piece takes place, leaving Xenophilius (working as a journalist, with strange theories, but not yet married or the owner of a paper) the guardian of his younger sister, Luna. Luna is attending Hogwarts, and is in the same year as James Potter, Lily Evans, Peter Pettigrew, Remus Lupin, Severus Snape and Sirius Black. As with canon Luna is assumed to have sorted into Ravenclaw, and to be sufficiently 'different' that she gets trouble from people who consider her odd. The canon characters originally in this generation are all assumed to be in their canon houses. The scene opens in 1976, just after the OWL defence exam, and as in canon James and his friends have decided to dangle Severus in the air and humiliate him. Severus' only real friend, Luna Lovegood has arrived on the scene, however.
Further Note: This piece is currently rated 'T' and a one-shot.
"Let him down."
"Or what, Nargle Girl?" James Potter responded to the pale blonde-haired witch. "Or you'll hit me with a humdinger hex? Or bounce me with a dirigible plum?"
"Dirigible plum… Good one, Prongs." Sirius Black snickered.
"Ask a herbologist. Anyone well-read acknowledges that dirigible plums are real." the blonde-haired witch responded. "And 'or what?' 'Or what' I inform the headmaster that your girlfriend, the fifth year Gryffindor girl prefect, stood by and held your cloak whilst four of you attacked a student from another house, that foursome including the other fifth year Gryffindor prefect. And if that's not enough, I write to my brother's friend, an up-and-coming journalist by the name of Rita Skeeter about it – including a mention about my theory that Mr. Lupin has the backing of the horned hasquatch conspiracy, which is why he's 'ill' every so often, off attending their meetings. Of course not everyone believes in horned hasquatches, and might look for more mundane explanations. I wonder if there are any there to be found?…"
There was a moment of silence, whilst the main actors in the two sides in the drama playing out by the lake glared at one another, and all the other pupils watching stared, enthralled, and wondering what under-currents were going on."
"If you spread any lies about Remus…" James Potter narrowed his eyes.
"Let Severus down, and I won't need to. This time. And not ever whilst we're at Hogwarts, if you lay off on unfair ambushes. Severus can handle himself perfectly well, if you want to take him on, normally."
James Potter flicked his wand, muttering something, and Severus Snape dropped to the ground, still spluttering soap bubbles.
"There." James said.
"So long, Nargle Girl." Sirius said, as the four fifth year Gryffindor boys, and Lily Evans, turned to depart.
"All your friends are crazy, Snivellus." Lily Evans glowered at Severus in passing. "They're either psychos like Mulciber, or lunatics like Loopy Lovegood here."
And then the crowd parted, and the Gryffindors left.
Luna Lovegood went to Severus, and patiently helped him to his feet, as mutterings and whispers went around the crowd. Severus retrieved his wand, and flicked it, to produce a muffling spell around himself and Luna.
"I don't think the headmaster would let you spill Lupin's secret." Severus said.
"I'm crazy. I have the privilege of saying whatever I want, to whomever I want. And just occasionally, I turn out to be crazy and deadly serious." Luna shrugged. "The headmaster couldn't really stop me, without looking an idiot. And anyway, whether the headmaster would stop me or not, James Potter couldn't afford to risk that he wouldn't. Now: next weekend, I have a table booked for us, a pot of tea, and a plate full of scones at a particular Hogsmeade teashop. And so long as James Potter and co. don't do anything such that I have to invite someone else along, we can get some serious snogging in, then…"
Author Notes:
Severus arrived at Hogwarts acquainted with Lily Evans, as in canon, but Luna Lovegood soon caught his attention, (Luna was obviously clever and he perhaps felt sorry for someone he perhaps perceived as an outcast like himself) and he started to hang around with her. Luna Lovegood was much too weird for Lily Evans and Lily's pride however, and Lily's relationship with Severus fell apart much faster than the canon one, ending when Lily giving Severus an ultimatum to 'drop the Lovegood girl', which Severus ignored. The Death Eater wannabes in Slytherin who sometimes patronise Severus are (her weirdness aside) relatively fine with Luna (they make a show of tolerating her, and not making public fun of her), since she's Severus' friend and a pure-blood.
I think that, post-Hogwarts, Luna and Severus end up 'an item' and Luna takes Severus off looking for snorkacks for a year or two (this version of Luna doesn't mind the Death Eaters, but she has a nasty feeling that they're going to lose the first Wizarding War, and she doesn't want herself or Severus anywhere near them (or Lord Voldemort) in case they catch 'loser's lurgy' from them.) Sure enough, Augustus Rookwood brings to Lord Voldemort's attention a prophecy apparently about him, which Voldemort infiltrates the Ministry to hear for himself, and the Potters wind up scrambled (Voldemort's first choice of target) but (alerted by Voldemort's attack on the Potters, that Voldemort knows about the prophecy, and operating on one of his inspired guesses) Albus Dumbledore is ready when Voldemort moves on the Longbottoms 'just to make sure' and young Neville Longbottom ends up after a fierce battle as The-Boy-Who-Lived.
At which point, if Severus is still interested in helping Lord Voldemort and his 'Death Beaters', Luna will cease to object. She might even help him look for Lord Voldemort (vanished after his defeat). She has scores to settle with the world in general, after all, and some of the lessons she's learned at Hogwarts have been different ones from those her canon counterpart picks up a generation later...
Update: (November 6th, 2016)
In response to at least one of the early reviews, as far as I can determine canon Luna (at least until she becomes Harry Potter's friend, and is suddenly 'cool' in the wake of the events of Harry Potter and the Order of the Phoenix) draws little but insults, invective, and cruel tricks from the majority of the Hogwarts pupil population who regularly have any contact with her. I do not believe that a Luna born a generation earlier would draw anything better than jibes from James Potter and company, at the height of their schoolboy swaggering. Yes, there is evidence that at least some of the Marauders in their school-days can be remarkably kind and loyal to members of their own number, but I believe that any sense of beneficence that they may have for their fellow human beings stops not far beyond that point. I do not think that their schoolboy selves would be capable of being sympathetic to such an 'obvious' figure for 'fun' as Luna, let alone a Luna that 'Snivellus' is being nice to and whom none of them happen to be actually 'crushing' on.
As regards Lily Evans, it seems to me that Petunia was not the only daughter in the Evans family to be born with more than a little sense of pride, nor possessed of an ability to (rightly or wrongly) hold grudges with remarkable tenacity if she decides that she has been slighted or embarrassed in some way that she considers unacceptably noxious. In this universe, I think Luna may have said something outré to Lily in their first real meeting (possibly something such as a sincere and very socially uninhibited enquiry along lines such as whether muggleborns actually have mud for blood?), and it was fifty-fifty whether Lily thought her interesting and decided to be patient and answer or whether she took offence and increasingly disliked and loathed Luna; as it happened, in this universe Lily ended up coming down on the 'take offence' side, and the rest, as they say, is history.