Hm. Loki medical neglect. Loki being prohibited as a child from seeing the palace healers for fear that, with their magic, they’d discover Odin’s secret. With them forbidden to touch the second Prince, only his mother left to heal him. As the only mage who knew his secret already, only his Mother could heal him. The secret kept from its subject even when Loki inevitably learned healing magic, because his own help is all he will ever get. That lesson sinking in further with every passing century, as the consequences of such a decision pile higher.
Loki going to his mother less and less as his skill with seidr improves, but not in a way proportionate to his actual accomplishments, shame driving to hide injuries above his ability to repair them, for fear of being so childish to “run to mother” for every “little” injury. Frigga coming, as always, to the most frictionless, comforting conclusion, instead of the correct one.
Loki throwing himself into his study of seidr because he needs it, isolating himself from the reckless danger the others throw themselves into daily, being obliged to heal them when they discover his cowardly, womanly, talents and never once considering why he, who despises battle, would have devoted so much time and effort to such a skill, where he would have gotten all the practice. Loki getting good at glamour and illusion as well, more hated womanly arts, to hide the signs of weakness that everyone already expects from him.
Loki getting the idea that perhaps he is uniquely weak, since all his injuries seem so much worse than everyone else’s. Loki being branded a liar when he mentions his injuries, damned if he does, damned if he doesn’t. He must have been lying about having been hurt in the first place, for we would have seen him in the healing halls. He must be faking still being affected by such a wound because anyone else would have been healed by now.
His fighting style developing to rely on distance, on tricks, on underhanded illusions, on taking down the opponent quickly enough that they never get in close enough danger to hurt him. The others, embarrassed, learning the exact wrong lesson from his dishonorable fighting and working to hit him as hard as possible on their first opportunity, so that he will not once again walk away from a spar unscathed.
Loki becoming more vicious in the battles he cannot avoid, since his opponents don’t seem to mind hitting him to injure at all. Since when he does the same they are fine the next day even if he is not. Not that the consequences they each face as the aggressor causing the injury aren’t also neatly reversed.
Loki developing a reputation for not wanting to be touched, for the way he flinches at and avoids such casual gestures of affection as a heavy pat on the shoulder. Prince Loki is so standoffish and cold. He doesn’t even let his brother close.
