Odin's firstborn son was a boy, big and golden and happy. He was full of laughter right from the cradle, with an infectious smile and a laugh that Frigga's handmaids fell over each other to coax out of him.
Frigga was the first to notice that one day it was Thor who, by gambolling and making faces and chewing on his toes while looking at her upside down, cheered a heartbroken maid into smiling at him-- and he barely crawling yet.
Frigga also noticed how the concealed but faintly noticeable bruise on the maid's cheek disappeared after she had cracked a watery smile at the baby and picked him up to cuddle.
They were sure of Thor's spark of seiðr by the time he reached a half century in age, toddling rambunctiously. His nurses swore up and down that they were trying so hard not to lose track of him, but every time Thor went to wobble energetically out of a room, a vase would break or an aquarium shatter or something else cause a commotion behind the nurse, and by the time they had tended to the hazard, Thor would be long gone. It could only happen so many times before Frigga and Odin recognised the cause.
"He is my firstborn son," Odin said, frowning deeply. "If we do not encourage it--"
"We might stamp it out of him?" finished Frigga delicately, dangerously. "He is your son, Odin. Precisely. What, pray tell, would this realm be if some red-haired young man had not dared to put on skirts all those millennia ago?"
"It is no longer strictly necessary to follow that custom, I think," Odin muttered, but that was that.
Thor learned seiðr from both of them. Odin walked in on Frigga and his two hundred year-old son in skirts only once, Thor blushing furiously but too eager for the lesson to refuse, and quickly Odin left them to it before Frigga could tell him to join. From Odin, Thor learned battle magic, unlike the more delicate weaving of what was by then known as "woman's work," but frowned and grew bored when he found it could not make nearly as many people laugh.
Decades passed, and the court rumbled with dissent as the beamish mageling who ran the corridors of the royal palace grew more and more confident in his tricks.
They were harmless things, swift and almost painless, always aimed to give Thor and everyone else (save the victim) a laugh. Odin would have discouraged him save that Thor had a sense of honour even in that; he was an even-handed trickster who never bullied or picked unfairly at one person. Sometimes, Frigga noticed, Thor's pranks were vengeance-- but never for himself, only for another, a scorned woman or a bragging warrior who Thor felt needed to be taken down a peg.
But the court disapproved.
"Do you forget," Odin finally roared to the hall at large, one night at a feast, "who it was that built this world, and how?"
They had tried to, it seemed. Odin's words made them quiet their tongues, but as Thor grew older, they none of them seemed to change their minds about the little seiðmaðr their rulers were raising as an heir. That Thor was a friendly and buoyant boy probably spared him a great deal of grief, as did the fact that all his running and scrambling about had made him strong, but it could not make up for everything.
"What kind of prince can't even hold a sword?" demanded one thane's son, in words that Frigga knew came from his father's mouth.
Thor's face was dark. "Damn your swords," he said. "They're no fun, anyway."
Frigga pulled both boys' ears, Thor's for his language. She did not, however, pull it when every sword that the thane's son picked up for the better part of a month turned into a snake. Well, a wiggly sort of creature, anyway.
"They were supposed to be manhoods," Thor muttered, and buried his face in her lap, but he was giggling and Frigga couldn't help but give a shocked laugh herself.
He giggled significantly less when she sat him down for a talk about the body and its parts and functions, male and female both. Frigga's serene gaze in the face of Thor's squirming discomfort told him quite clearly just what that was punishment for.
Thor was nearly three hundred, old enough for Frigga to have seriously begun worrying what would happen when it was time for him to join his agemates in training, when the war with Jötunheimr finally ended. Odin came home missing an eye and holding a baby.
Thor had a complicated relationship with books: he hated them on the principle that he could not run around while reading, but adored them for the knowledge they contained. Nonetheless, after Odin's return he immediately buried himself in the library looking for a spell that could fix his father's empty eye socket. Frigga found him asleep on a book far above his ability level more times than she could count.
But it was a blessing, for the baby Odin had brought her was trouble enough on his own. A little jötunn child, half-starved and noisy at first-- and unknown at every turn. When Odin told Frigga that Loki, like all jötunn children, suckled not milk but blood, Frigga had to sit down quite hard. The sharp little fang in Loki's mouth was the cause of more bloodied gowns than Frigga knew what to do with.
Yet for all the promise of his heritage, Loki grew to be a quiet and serious child, nothing at all like the boisterous bruiser Frigga and Odin had expected. He was ever his brother's audience, pleased to smile at every joke, no matter how unfunny, as long as Thor would carry him around on his back or lift him up onto a garden wall or eat dinner with him. And no question about it, there was seiðr in Loki too.
The sight of what Thor faced, as he began his official training and grew sullen at having to spend his time learning about things that did not sparkle or burn or change shape or turn to smoke, was enough to make Odin grimly reluctant to raise Loki the same. At the same time, Frigga counselled again how unkind it would be of them to deny their child's nature-- particularly in Loki's case, as a young warrior with no learning in seiðr could cause only disaster if his inborn ice magic ever burst out of him.
Given the circumstances, teaching him seiðr was not a question: there was no choice but to teach Loki at least enough magic to manage his natural gifts. The problem still remained, however, as to how much knowledge was enough. Did they give him the training that Thor had?
Yet Loki nearly solved the problem for them, for he was keen and observant in a way that Thor never had been. His eyes cut into the complexities of situations, whereas Thor only ever cut into people deeply enough to know what would make them laugh or be laughed at.
Loki knew what torments a seiðmaðr faced among the Æsir, and he wanted no part of it.
"And will you forswear yourself, then?" demanded Frigga of Odin in a low and angry voice, in the dimness of their bedroom. This woman in her dressing gown, hair and tongue unbound, was not one the court would ever see as their queen. "Raise your sons on the oath that they must be true to whom they are, that you will never see their true selves curbed for Asgard's prudishness, while you tell Loki nothing of his father?"
"Do not debate semantics with me."
"Should I announce Loki to the court, then?" Odin snapped. "Would you have me endanger the claims of both my sons to the throne?"
"I said tell Loki of his parentage," Frigga sighed, gentling. "Surely it will be necessary to tell him wherefrom comes his affinity for ice."
Odin turned his face to look at the hearth, firelight gleaming from his inscrutable eye patch. "He is clever. He could not not know then that I had already lied."
Frigga laid her hands on her husband's shoulders. "He is not Thor. He will understand the necessity of it, and control his emotions. And if you fear to speak because you think he will be angry now..."
"He is not old enough to keep the secret."
Frigga laughed. "Loki was born to keep secrets. Teach him politics, my husband, and Asgard will never be the same."