one of the reasons i'm excited for the next time we visit the mare jivari is to learn more about the bakunawa. this is mainly about it's relation to rhinedottir because from everything we know so far, the bakunawa is very different from her other creations.
in enjou's notes on the bakunawa he says that it's immortality doesn't come from the power of "life" like rhine's other creations. but rather a "a more transcendent form of Abyssal power that may be beyond even our Order's understanding." enjou also states that the bakunawa doesn't have intelligence, which is very different from the other abyssal dragons that rhine created. and the bakunawa is an out of control creation of rhine's that attacked her and ate part of her body.
one way we can see how it's immortality is different from elynas and durin's is that it's always active, and the pieces of it's body seek each other out to reform the entire bakunawa. but with elynas and durin it was more like they were still alive and it a form of stasis, but it would take an outside force to bring them back to life completely.
additionally with elynas and durin, it seems like rhine released them into the rest of teyvat on purpose, but with the bakunawa it seems more like it escaped, attacked her, and then came to natlan just looking to devour everything.
