The energy Ichigo and his sisters have isn’t Asgardian magic, or even jotunn; not quite. Though the flavor of it reminds Loki of Fa- of Odin’s Valkyries, and that’s something he doesn’t want to look at too closely.
But energy is energy, and if it isn’t exactly like, it still has patterns. And patterns can be manipulated.
He starts with healing. Ichigo, after all, is always getting into scrapes. One way or another.
Isshin’s hidden his children’s power so well, no one not deliberately searching would find it. And if they did, Isshin’s heritage (whatever that might be, he’s much more than just a shinigami) would drown any faint trace of other like a drop of ink in the ocean.
Yet Loki has found raindrops in the sea, and runes of power in the dust pile that had been an ancient tome. He sinks into a kenning of blood and bone, and knows.
He ought to think of her as Frigga; surely she, of all people, knew he was no child of hers. But – and this is painfully, achingly clear in a trickster’s memory – she never claimed he was one of the Aesir.
Odin’s son, yes. Her son, yes. But she had never said he was not a jotunn.
So. Now he knows why little Yuzu, all of five and trying so hard, has never burned herself in the kitchen.