Leviathan Idea

A long leviathan kinda like Tiamat or Lahamu like from monsterverse (picture as refrence for basic body shape it could have). Maybe have it able to burrow simmilar to the ice worms but using their two arms to dig. It would have nests in underwater caverns and you have to go through their tunnels to get to the nest, their nests having some sort of ore, blueprint, or maybe a black box, with the children sleeping in the cavern nest and waking them up causing them to let out loud chrirps calling for their parents. On the surface of the ground ocacionally have the leviathans surface and swim around the tunnel entrance fhey made. Grabbing any medium fana they can find and forcefully thrash to kill it and bring it back to the tunnel system, having it somewhat ignore the player unless you are in their nests/tunnels or getting close and annoying them (maybe with the multi tool or sonic resonator) but target the tadpoles, potetially viewing the big submarine as big of a threat as other large leviathans. The children could potetially try to atack the player but could also be friendly and playfull to them if you give it a fish before they start calling to their parents. Potetially doing the same with the adults if you drop a large amount of fish for the adults to atleast tolerate you and allow you to play with their kids. Probably having either one big colony or small familys spread fhrough the map and if you have one fsmily tolerate you jt wont affect the others so youll have to actually go through the process of befriending different groups of them.

bro goated for the Tiamat reference