1) Maybe she always alone (no one to speak, hug, kiss or play) so humans have good company
2) She intelligent, so she think humans are people and people is not a food
3) She protector (or mother) instinct and she think humans are kids or babies so she come if everyone are good and she play with them.
4) Or humans are cute so she want have a human like friend or lover and she have difficulte to choice.
(My ideas)

Well, your first point DOES hold some ground. She lives a solitary lifestyle of living and hunting under the waves :)
Second point is valid as well. She can speak and talk with the humans.
I very much doubt she sees them as anything more then entertaining tbh. She is WAY out of their league for sure. In her mind at least.
The humans ARE cute yes, and funny. So tiny. Yet again, they are TINY, not very useful for anything but visual entertainment jajaja!
Thank you! This has given me some thoughts!

Says the one who labeled it AS macro/micro :P

Regardless this is delightful and sweet! Perhaps she just desires company and it's lonely out there under the waves.

Humans provide a smaller, if appreciated form of companionship, much like how larger whales will befriend dolphins and sometimes humans, or at least be nice/cordial/curious with them.

Based on her curvature/human-shape-ness and if she's just as hard-wired as humans are towards things like pleasure and reproduction, she'd probably desire.... more lewd companionship from the most adventurous humans, could see it as a once on the full moon sort of deal where all the most athletic/courageous/foolish young men and women gather up on the shore and help her with her... problem.

You got me D:

Thankyou! Yes most certainly! I'm sure it gets lonely down in the depths of fish who do not talk back :)
I kind of thought she might have that dragon-sized life span. But still generally young even in that.
I suppose in that time, with her sharp dragon mind, she has likely learned to understand languages of some whale and dolphin species, as well as many of the human languages spoken on the shores of the ocean she inhabits (Pacific?) The latter of which she can speak, thus allowing her to communicate with the land dwellers!

She strikes me as a sort of 'queen' personality. Not arrogant, but certainly thinks herself a being to be respected, considering her size and placement on the food chain.
Comes up from the sea in various places all around the ocean, visiting lost island tribes, or larger coastal populations to interact with the humans that have so quickly spread across the globe. To talk and hear of the new events happening in their generally unexplorable (for her) lands.
Assuming this is developed humans/Earth, I'm sure she knows, to an extent, their polluting of 'her' sea, and likely harbors some resentment.
But considering the fact the humans have warmachines that are more then capable of hunting and killing her, she will keep her mouth shut, and her actions un-harmful.
Speaking of which, she probably knows the shipping lanes of the boats as well as the migration routes of her foodsources. (Perhaps even aware of the human transport 'bird' vehicles?)

I suppose at her size, there are really only two things that could ever matter. Food and Pleasure.
Not like money is a thing for her. No place to work, or buy things.
Food is generally easy. She just swims wherever she likes and eats whatever she finds, or hunts known migration routes.

But pleasure? Self-pleasure sure, but I'd assume the sea is generally void of giant sea dragon creatures. Perhaps one too each ocean?
Lady has too much time and too little her size :) I do not know what the humans could do for her in that regard. But I'm sure any who are too enthralled with her curves and immediately go to spread their seed before her, without her permission, are destined for a very painful, if not dangerous punishment flick of disgust.

Gotta get permission :)

If she can speak both Whale/dolphin and Human languages... then she can be more than just a queen, she can be a diplomat between humanity and cetacean kind... and perhaps give the latter some leverage in politics.

She could perhaps be a queen of the whales and dolphins in the pacific, who respect her for what she is, perhaps sperm whales offer her food on occasion in the form of calamari. This probably also means the age of whaling was... cut short fairly early on once she put her fins and jaws down, and likely changed world history significantly as a result.

I could see island nations and other oceanic polities having far more connection with her, and of course 'leverage' with other nations as couring favor with her and by extension the cetaceans, would make it allot safer to move about on the ocean... I mean what better form of lifeguard/coastguard than a pod of dolphins or Orcas? Or a long distance hauler of goods than a ship with a blue-whale pulling it.

Such services could be repayed in materials and services the whales can't normally get, with the dragoness acting as a medium/negotiator for her 'people' as well as the people on land getting goods that normally are hard to acquire, such as pretty corals and shells, kelp and shellfish (Oysters and such) and more later industrial goods such as ores and nodules of zinc/copper/gold/silver/phosphorus found by and assisted in mining by the deep diving whale species.

As to the pleasure, she probably also likes other things beyond just sex, Music for one, Artwork (Especially art that can be brought underwater) and maybe as humanity gets more advanced, they can build things for her that float or perhaps a 'sunken palace' for herself, with air chambers that she can have visitors come under the ocean for her to play with/visit with on her terms (Which garners more respect from humanity for being the ones to get their feet wet, instead of her fins dry)

As to others of her species/numbers per ocean, that means there are 7 such dragons.... Though I feel with a place as big as the pacific, there should be maybe 3 others... perhaps all of them her sisters, with a male dragon lording over the arctic ocean, and one in the circular current around the antarctic ocean. The rest in the atlantic/indian oceans could be female... Maybe one in the mediteranean might be a male or perhaps a female... maybe twins and add things to the mythos of the greeks especially if they're very old.