Edit: thank you guest reviewer for letting me know the text glitched!
Jez… almost a full year to finally update this… I couldn't get the right feel to this for the longest time. I've got an outline of how I want this to go at least, probably not long but hopefully its something!
Sora didn't know what to feel anymore. After a full two hours of ignoring him Sora finally gave into Riku's attempts to talk to him from the top of the tank. He reached up and grabbed the older boy by the shirt pulling him into the water. Sora clung tight to his boyfriend, his tail unconsciously wrapping around Riku's waist to hold him closer as Sora cried into his chest. Luckily there was the alcove nearby so Riku could sit on top of the rock and not get pulled under, he sat rocking and cooing to Sora to what felt like ages.
He was afraid of what would happen to him as time went on, worried about the other worlds and his friends while the team was a Keybearer short, confused on just HOW this particular change was triggered as it'd never happened any of the other times Sora had a mission after romping with Riku, and also frustrated cause apparently the magic that changed his form wasn't the only thing on the fritz as both his Keyblade and his spells refused to work when Riku suggested practice exercises to keep his mind off things. The only thing he conjured was sparks of thunder that enveloped his body protectively and somehow managing to make the artificial current in the tank change directions slightly. (just why does Sora have water magic in 3 all of a sudden? ;3 )
But what bothered Sora most right now, is that something in his mind felt satisfaction. He had the perfect shelter, there weren't any larger predators around he was given plenty of food and sleepy, he felt safe. Safe because Riku was nearby, near enough to watch over him, to care for him, to protect him. Safe with his mate to provide for him while he was vulnerable and nesting.
Sora was scared and angry and confused, but he also felt safe.
The feeling was not the same a week later.
He couldn't help but get more and more irritable, the tank itself was the perfect shelter yes but it wasn't enough, it was too small too still, his muscles felt both cramped and full of energy, he was bored out of his mind, the food Riku brought him had dulled in his mouth, it wasn't fresh enough to still have the warmth of life, it wasn't as satisfying as catching it himself would be.
Something about the bed was bothering him too, there was an idea of instinct in his head on how to make it into proper nest, yet it wasn't good enough no matter how many times he tried, nothing made it feel good enough and he didn't have the right materials at all.
Worst of all was his hormones, he needed Riku, craved Riku in the worst way both intimately and for comfort with all the fears in his head and after waking from muddy dreams with a familiar, dreadful cackle ringing in his ears, but he just found something wrong with him every time they got close. Sora had always liked the way Riku looked but Sora's instincts found him off putting now for some reason. What was left of his wavering patience reasoned out that maybe it was just how separated they were like this, Sora couldn't come out of the water and Riku couldn't stay in for very long…
Sora had gotten to a point where he couldn't even use real words anymore. Any time Riku tried to talk to him he'd get clicks and trills in response. Any time he tried to join Sora in the water the brunet seemed both overly clingy but stand offish at the same time, pushing him away with flared fins. Riku knew Sora wanted something from him, but with these new behaviors and lack of actual communicating he was at a loss.
Riku had asked Yin Sid about it but the wizard was still gathering information on what he could. Destiny Islands had no native merfolk, as such they had to piece together things from what they knew about mers from varying worlds as well as any natural fish that looked anything remotely like Sora.
The best they can figure is that Sora was forced into some form of protandry, in which his reproductive fish genes have switched from male to female, even if overall he is still male, and theoretically was Riku's sole dominance over him that might have triggered the change. But it didn't explain just why it hasn't happened before. Especially since any species they found to compare to Sora were incapable of such.
His behavior however was a total guess, while they did see signs that he was trying to fill his bed with things he never seemed satisfied with it, he picked up things from around the tank and arranged them then emptied it all out again with a screech and start over. His fins seemed to respond to his emotions too, flaring up to make himself bigger when he was especially angry, or lying flat when Sora curled into himself after waking from nightmares. More often than not Riku ended up spending most the night sitting on the alcove roof holding Sora just so he could sleep.
The only other thing Riku could clearly read off him was the worsening claustrophobia of being in the same room for so long.
Finally, one day Riku had been talking to Yin Sid in his office about their options when they both heard a sharp crack along with a rush of water. Riku rushed back, only to see His Sky draped out on the floor, a hole in the upper part of the tank and the water pouring out at a steady pace.
As Yin Sid hastily repaired the damage Riku gathered up the flailing merman in his arms, lack of oxygen had Sora twitching uncontrollably in instinctual panic. With a powerful leap Riku lifted them both over the lip of the glass and back into the water holding himself afloat while supporting the smaller. It took only three breaths for Sora's head to clear and that was all he needed to start writhing, screeching terribly with something close to tears in his eyes. Pent up emotion and energy had started leaking into his magic causing thunder sparks to shoot out into the water, Riku hissed in pain gripping Sora tighter, his heart aching at the pain his light was in. There was blood in the water from where Sora had rammed into the glass.
They needed help, they needed answers, Riku didn't even pause to think it through as his Keyblade tore a portal through space.
Biologist nerd in me finds it interesting that fish can change genders in addition to the frogs mentioned in Jurassic Park along with a few others, wiki it if you want more info~ wiki/Sequential_hermaphroditism and yes I know it says fems are the bigger ones but we will ignore that bit, I like Sora small :3 As for his magic only using thunder (with a hint of water): fire isnt great against water, blizzard is probably hazardous to tropical fish, I'm ignoring other elements, and no Keyblade is just for plot X3 plus I think itd be neat if thunder manifested into an electric eel esque defense mechanism?