While referring to the direct offspring of a mortal and a god, this is very uncommon. Mostly because the gods do not have the ability to enter the mortal realm themselves just as no mortals has ever crossed the Cosmic Breach. There have been a handful of exceptions throughout recorded history but these are mostly technicalities except for one. Even mortals rarely can cross the breach, only when they have entered into a state of reverence that they must choose between becoming a god or returning to their mortal lives. For the Eleleth these are known as Veneraris and for the Ornir, the Einhjar. Lesser beings from the planes and mortals can end up on the other side of the breach through rare black portals but relationships with the powerful deities is unlikely as it would draw attention from beings above them. The next story getting away with it for decades is a rarity and still misunderstood in how it was allowed.   In recent centuries Sootha somehow crossed the plane and shapeshifed into a woman named Ilma. She used the black obelisk that is now deactivated on milos to enter into this world. Some mortals have shared stories of accidentally walking around other planets, transported there through black doorways but never has a god been able to enter the mortal plane until Sootha. She loved the man named Oceanus and spoke to him in his dreams. Somehow from the time of these dreams to after The Six freed man from the Onyx Aelfe, Sootha disguised as Ilma found a way to sail the seas with Oceanus. She even used her godly powers to shape earth under the water, creating alongside her husband the nation of Pacura. She slowly lost her mind as she was still technically in the godly plane of Naativus. She grew more powerful and lost control of her powers, almost causing the destruction of her families island home. Oceanus killed his wife while tempering her storm with his powerful vestige the Imperius Trident. Their 9 children lived on the nine major islands created by the couple and are the only true demi gods written of in history. Sootha's spirtit returned to her godly realm while her body turned into the 10th island of Pacura.   A part of a god can be sent down to the mortal plane but the being has its own sentience and can obey or abandon there gods once given life. That is why these can be risky but the Eleleth have sent down Soels, beings born in the Black Ocean and gifted the opportunity to take form in the mortal plane, usually to pursue a goal for their deity. The Ornir have a similar ability to create a Drengr, also sent to the mortal plane to achieve a goal. Others have also been pulled from the planes in the Black Ocean to Galfin but they still have a master, even if they didn't get sent directly by them. Paimon was pulled from Baan during a botched sacrifice, Rezial of the First House would have no idea that Paimon is on Galfin but Paimon is technically one of the Drengr of Death.   Also a note on gods not being on the mortal plane, one god was caused enough issues in the bLack Ocean that rules were bent and broken millennia ago for Merkayne to lock his brother Vlox within the Pit, a location the brothers built in tandem during the 2nd era.