Encantado

/*From wiki, would actually make a lot of sense to adopt, have to work it out first:
New World Amazon river dolphins, known by the natives as the boto, encantados or toninas, are very prevalent in the mythology of the native South Americans. They are often characterized in mythology with superior musical ability, seductiveness and love of sex that often results in illegitimate children, and attraction to parties. Despite the fact that the Encante are said to come from a utopia full of wealth and without pain or death, the encantados crave the pleasures and hardships of human societies.[55]
Transformation into human form is said to be rare, and usually occurs at night. The encantado will often be seen running from a festa, despite protests from the others for it to stay, and can be seen by pursuers as it hurries to the river and reverts to dolphin form. When it is under human form, it wears a hat to hide its blowhole, which does not disappear with the shapeshift.[55]
Besides the ability to shapeshift into human form, encantados frequently wield other magical abilities, such as controlling storms, hypnotizing humans into doing their will, transforming humans into encantados, and inflicting illness, insanity, and even death. Shamans often intervene in these situations.[55]
Kidnapping is also a common theme in such folklore. Encantados are said to be fond of abducting humans with whom they fall in love, children born of their illicit love affairs, or just about anyone near the river who can keep them company, and taking them back to the Encante. The fear of this is so great among people who live near the Amazon River that both children and adults are terrified of going near the water between dusk and dawn, or entering water alone. Some who supposedly have encountered encantados while out in their canoes have been said to have gone insane, but the creatures seem to have done little more than follow their boats and nudge them from time to time.[55]*/