Considering your recent material in the Subnautica AU, I do need to ask a few things about the sirens as there's a lot of mystery and I may or may not want to make something for you in this AU (And no, I'm not expecting it to be canon)
1) DOES the coloring of certain siren genders mirror that of earth's fish? Like, are males brighter than females?
2) HARD QUESTION! Are Sirens born from eggs, like most fish, or are they born live, like whales or sharks? (Someone's gotta ask the hard questions about a species, right?)
3) Do they show color when they're born, or does their color change over time?
4) Are Sirens in this world solitary creatures like in popular folklore? Like, do they value their independence, or are they willing to ask for help?
5) Admittedly, this one is less on the sirens and more so my stupidity on this game talking, but what are the Interlopers and why are the Sirens so...what's the word for it...nervous about them? Scared of them? Not sure how they feel about them or who they are
I hope these aren't too weird at all...
Oh ho ho hooo! Time to break my lore brain! I'm glad you like my AU so much! :D Alrighty! Here we go!
Putting everything below a cut, cuz there's a lot :D
That is correct! The more vibrant the colors, the more likely the siren is a male. However! There are cases were a female may have one or two bright colors (the different subspecies and whatnot), in that case; look to the the fins. Male sirens will always have colorful webbing and fins. Sun's fins are bright orange and yellow with red quills. Moon's fins are bright blue that fade to a little but still popping blue. Eclipse's fins are bright orange with some red. A female siren would not have colorful fins and webbing, it would be white, silver, or black depending on the subspecies. :D
The siren leviathans do indeed lay eggs, like most leviathan species in Subnautica. The eggs have a tougher "skin" than normal fish eggs though, making them sturdy. Also! Most mated pairs only lay one or two eggs, that is how high the survival rate is for siren :D (but that depends on if the adult siren doesn't kill their prospective mates) They are also always white, silver, or black, depending on were they were laid and subspecies. This leads to your next question, friend!
Siren's do not show color until they are old enough to hunt on their own. Until then, they remain muted in color, to better blend with their surroundings. White for shallow areas or arctic. Silver for deeper waters, reflect colors better to blend with any area. Black for the deepest parts of the ocean, blend with shadows for survival.
The sirens in this world prefer to travel in pairs (like Sun and Moon). When young, they will find another siren and will bond with them (familial, platonic, or romantic), thus becoming a pair. The two together will hunt prey and thrive. There are some, though, who grow too territorial and will kill their partners (like Eclipse). This is rare and only occurs with the more territorial subspecies (but they will not kill their mates, only family and friends cuz territory). Sirens will always turn to their partner first and foremost before seeking assistance of other species.
The "interlopers" are the precursors/architects from the game! "Interloper" is just what Eclipse calls them, since they invaded his home and interfered where they shouldn't (in his opinion). Sun and Moon don't really know much about the Architects, since those guys left WAY before Sun and Moon were born, but Eclipse... Well. Eclipse is a LOT older than he acts. He was a hatchling when the Architects basically doomed the planet. He and his partner (who was alive at that time) fled to an area with enough volcanic activity that the Kharaa virus was unable to infect them ((hence why it doesn't show up in my AU, the "Hot Spot" is a volcanic center that "cleansed" the area when the volcano was still active. It is currently dormant during the events of the stories)). Eclipse absolutely hates the Architects and blames them for the state of the world (such as the near extinction of many leviathan species like the Sea Emperors)
These were wonderful questions and it was a blast answering them! Feel free to poke my brain any time! A lot of what I think up doesn't actually get written in the stories due to them being mainly from Reader's perspective (tho Eclipsed Rhythm does show a bit of Eclipse's perspective every now and then)