Disclaimer: I own none of the characters from Blue Drop, they all belong to Akihito Yoshitomi, and I'm only borrowing them for a bit. This is based on the Blue Drop manga, both the original series and the new Tenshi no Bokura one. It also has yuri content.
Blue Drop: Historical Context
Yui sometimes wondered what people thought when it happened. The spaceships of the Azume filling the sky, the beautiful women descending with tranquil smiled then... exploding as they sacrificed themselves as living weapons. Did the people there know this was the end of their way of life? Did they know that everything had changed?
For the last 1000 years the Azume had ruled over the Earth, working through proxies in the civilian government as well as directly interfering. They lived and walked among us every day, these silver haired, blue eyed beauties, but no one really understood why they had came here or what, ultimately, they really wanted.
Shaking her head Yui got up from where the black haired girl had been sitting on the shore, staring out at the sea. Thinking about such things wouldn't help them, and she had things to do. The blue eyed girl clambered over rocks as she headed up the road, seeing the rubble of a ruined Azume ship off in the distance, the wreckage of a skyscraper nearby. The world was littered with sights like this, the ancient aftermath of that incredibly short war.
"Hey," one of the sentries nodded, sitting with a casual air outside the old office building they called home. His relaxed pose was contradicted by his wary eyes, and a pistol sat concealed but within easy reach, just in case. "Mari wants you," he noted.
"All the girls want me," Yui nodded back, smirking.
He rolled his eyes, "Seriously, she wants to talk to you and the other cell commanders."
"Thanks," Yui said as she went in, then headed for the stairwell and went up two floors. "So," she said quietly as she entered the room, men and women working and talking busily, "what's so important you had to get me here."
Another half Azume like her, Mari was a quiet but pretty girl, her eyes having the same alien look her's own did. "I think we may have made a breakthrough," she smiled as she pushed black hair back, "studying documents predating the invasion, we may know why..."
Yui's eyes widened, "Why the Azume came?"
Mari smiled slightly, "We think so." She took a deep breath, "You all know about the Azume's silver hair, blue eyes and pale skin..."
"They all look sort of alike, too," Shouko noted quietly. She had once been in line to be turned into a weapon to neutralize left over ordinance from the Azume/human war, and was rescued by Yui before they could kill her. Now she was a member of their resistance, helping fight the Azume and their willing human collaborators.
"In the early days of the Azume's arrival, that not only did they take over but they..." Mari blushed, "took advantage of human women."
"Heh," Yui smiled wryly.
In fact, that was something of a understatement. The Azume had been like kids in a candy store, seducing willing and occasionally some not so willing young women. Whole areas had been declared their personal territory, no men allowed in, and any woman found wandering there was considered fair game.
"Obviously, we're exotic to them with our various hair colors and other features, but there may have been a more important reason," Mari said briskly.
"Oh, really?" one of the men in their group wondered, his brown hair falling rakishly into his eyes.
"I believe the Azume are suffering the long term effects of inbreeding."
"What?" Shouko blinked, sitting up in surprise.
Mari looked embarrassed, "I started suspecting something when I saw the Azume's version of a ancient sex manual... it's sort of their version of the Kama Sutra." She turned and fished around her desk, "Here, look at this."
"Wow," Yui noted, looking at two women in a imaginative pose.
"Get your head out of the gutter," Mari rolled her eyes, "and think about it."
Mari looked at the picture, a black haired woman twisting gracefully as a redhead played with her nipples and frowned, "What am I supposed to be seeing?"
"Hair colors," Mari sighed.
"Oh!" Shouko realized, "Azume don't have different hair colors!"
"Exactly," Mari nodded, "the original this document was copied from is very old, and at one time the Azume had a broader degree of physical variety."
"It could be this is fiction," Yui pointed out, "in mangas the creators used hair colors that never existed in nature..."
"Possibly," Mari conceded, "but we've found other documents that back this up."
"So, why inbreeding?" Yui asked.
"I'm no geneticist," Mari conceded, "but I talked to several medical scientists. It's possible that the Azume didn't evolve into their current appearance, but instead may be suffering a genetic defect similar to albinism."
"So why do they need us?" Shouko asked.
"I think," Mari was careful to state that she was speculating, "they want to use human DNA to undo the genetic damage, or possibly to simply add a greater variety to their gene pool."
"So how does this help us?" a young man had to burst out, "We can't stop girls from having sex with Azume!"
"Maybe, but understanding at least part of their motivations is a good thing," Yui pointed out. She gave Mari a admiring smile, "Keep pursuing this line of investigation, Mari. It could lead to more discoveries."
"And where are you going?" Shouko asked curiously as Yui headed to the door.
"I need some air," Yui answered evasively as she went out the door.
Mari sighed as Yui left, "I was hoping I could ask her to question Misato for me..."
"Why not ask her yourself?" a scraggly young man asked.
Mari rolled her eyes, "I'm not Misato's lover."
The home Yui had set up wasn't far from their base of operations, but you had to know where to look in the warren of abandoned buildings to find it. She navigated the maze with the ease of long experience, eventually reaching the section of building she had declared her house.
"I'm home," Yui called softly.
"Welcome home," Misato answered, the blue eyed woman smiling warmly in welcome. Her hair was black because of the dye, otherwise she would have looked truly unearthly with silver hair in the sunlight streaming in the windows.
"Hmm," Yui sighed as they kissed lingeringly, the taller woman pushing back Yui's shorter hair to caress her cheek.
Misato had made a hard choice, defecting from the Azume to be with Yui even knowing the fear and suspicion that the resistance viewed her with. Now she lived a quiet life with her lover, but despite joining their side Misato refused to divulge her people's secrets... or at least, doing so very rarely.
"What would you like with dinner?" Misato asked as she bustled around the kitchen, long black hair shining.
"Hold on," Yui put her hand on the taller woman's shoulder, "there's something I wanted to ask you..." Sitting down at the low table they talked as she sketched in Mari's theories on the Azume and why they came. Finally she looked at Misato, "What do you think?"
Misato poured them both tea, her expression oddly unreadable. "I don't know," she admitted finally, "it's possible, certainly, but no one in my generation has been informed as to why we first visited Earth."
"You don't learn it in history class?" Yui wondered.
"We're less... concerned with history than your people," Misato conceded.
Yui looked across the table at her, and once more was struck by the immense gap between their two species. A human would demand to know that kind of thing, to seek out reasons and causes, but the Azume seemed simply willing to accept what was. Even a half breed like her found it near incomprehensible.
"Never mind," Yui said, deciding to pursue it later. She looked across at Misato, "How hungry are you?"
"Depends," Misato smiled, "hungry for what?"
"Oh, I can suggest a few things," Yui grinned as they went back towards the bedroom.
Yui knew she would keep looking for answers, trying to solve the riddle of the Azume and their presence on Earth, but for now, it could wait. There was time to find those answers... eventually.
End
Notes: Based purely on speculation and reading bits and pieces of the Blue Drop manga.