...okay now I'm haunted by "what if the planet in Subnautica is in the process of developing its own indigenous sapient life after the Sea Emperors' deaths... and it's the reaper leviathans"
like the scanner calls them basically all brawn no brains but the fate of the Degasi suggests they recognize 'one of their own' and react to avenge/defend it, and their circling behavior means they're basically taking their sweet time sizing you up before they attack. They have dexterous appendages that could be easily adapted to tool use.
...And now I have a stray plot bunny because this thought is running into "if the warpers talk to each other using sophisticated protocols the radios can pick up, they're undeniably sapient themselves and their behavior patterns attacking you reflect this" and just imagining like. a reaper leviathan beginning to develop telepathic communication, trying to eat a disoriented warper who's lost their connection to the others, warper cuts reaper's mouth to get it to back off, and they end up in a standoff that ends up a conversation.
I mean just imagining a reaper leviathan as an early-sapience protagonist is very funny to me. My mental image constructs a teenager who lucked out genetically and got big faster than her neighbors so she thinks she's hot shit but is understimulated due to lack of a challenge, but whose primary emotional cope for basically anything she can't rip to pieces is to just Yell At It until it realizes how big and scary she is and backs down.
Oh my god you have no idea how much I'd adore an au like this. While I love the Architects as dearly as anyone, one of my biggest disappointments with Subnautica was that the intelligent species native to the planet got kind of left to the endgame/shuttled to the side, and then cut from the sequel when the main writer for Below Zero left. Like, I kind of get it, they wanted to have it be a big lead up in the og story and they had troubles in the next, but I want!!! More intelligent fish aliens!!! ESPECIALLY since the Sea Emperor has a concept of reincarnation, implying a philosophy and belief system that is unique to their species and doesn't require hands to maintain.
Though honestly, I think there's a solid enough baseline for that plotbunny already- Planet 4546B has recently undergone/was in the grips of a mass extinction event due to the bacteria plague, which means that there is not only a good deal of resource scarcity compared to the bountiful sea life that the ancestors of the current-day Reapers experience. Paired with that, the Sea Dragon Leviathans- known predators of the Reaper- have dwindled in number to only about three active individuals, which means that there's a lot more Reapers around to compete with. Assuming that intelligence is tied to adaptability, and that the Sea Emperors and Reapers share a common ancestor with the trait that formed into telepathy in the Emperor species, and you have a setup where natural selection is prioritizing Reaper leviathans who are not only mature strong enough and fast enough to outclass the other Reapers, but are also intelligent enough to outwit them. Size and quick maturity might have been a confounding factor in human evolution, but in terms of an egg-laying species, we can perhaps have them experience a longer incubation time, which results in a bigger hatchling. The increased size allows the baby to outcompete other juveniles, which in turn gives it the calories needed to help build that big brain that becomes a necessary tool once it becomes large enough to be seen as competition by adult Reapers. And as for the telepathy, being able to potentially settle territorial disputes and gather huntsmates, leading to less energy and risk wasted on members of the same species, and more being aimed at taking down more prey. It's a totally feasible fictitious evolution path, especially since the leviathans themselves are so mysterious
(Also, animals always tend to be more intelligent than people expect them to be. If the PDA was scanning for brain size in relation to muscle mass for the Reapers, its very well likely that it assumed intelligence based off of that, which we know from birds is not an accurate judgement.)
BUT ANYWAYS I'm also incredibly fond of this concept because ngl it also reminds me of how I write young dragons (especially from a specific tribe) where young female adolescents go through this big period of teenage badasseryhood where they essentially try to act like they're hot shit to try to intimidate potential rivals and test the waters to see which of the older females are starting to go soft so that they can go on ahead with their territory-claiming. For this specific Reaper, I can easily imagine a scenario where she's got an advantageous new mutation that lead to her outclassing her peers, but being in that awkward spot where she's just not quite big enough yet to challenge any of the older reapers, so she instead spends a good deal of time mucking about trying to work on looking Big and Scary, which involves a lot of tearing shit apart with her mandibles, roaring, and trying to stun prey into silence with her telepathy, which makes her Very Loud but also Very Good at Being Loud with her thoughts.
It would also be interesting to delve a little into Warper telepathy- the Architects bioengineered them into what they are now out of a probably-extinct species, and are thus likely responsible for giving them the ability to interact with computers and teleport, but since telepathy already existed in at least the Sea Emperors, the ability to communicate could either be natural to the species they modified, or implemented because they themselves did not think that they would be capable without being networked. What makes this so interesting, however, is that the Sea Emperor mentions that the Architects were incapable of hearing her (most likely because they were all networked; Al-an makes a very big deal about that, so they were probably closed off to outsiders and attuned only to other Architects), so it could be that the Warpers were ignoring this very loud new baby up until one got disconnected from the rest (perhaps due to mechanical failure?) and thus ONLY has Large Screaming Teenager to talk to. Which sets up a very interesting potential partnership between a very old, very exasperated, and very aware-of-vulnerability-Warper, and a very bored teenage Reaper who only knows violence and yelling, but is letting this particular Warper live because she's so bored out of her skull that the intrigue of helping them is better than tearing up the reef and getting tail-smacked by her elders for the nth time. Maybe the Warper can teach her how to use her telepathy better, and talk to her about the Architects and their purpose while they travel to find new parts to fix them with.
Fuck, that's a really good story prompt actually. I'm weak for accidental mentorship or adoption stories, doubly weak for inhuman apex predators being dumbass teenagers, and the potential language differences between two types of telepathy could be really fun to play with. Plus there's the advantage of getting to write about intelligent aliens that don't craft like us or built societies like we do, which is something that I personally think is severely underrated in sci-fi
