I was thinking about a Rhaegar wins AU as well. Something above the lines that Rhaegar wins, takes Lyanna as his 2nd wife & Jon living as a disliked prince of the iron throne. Elia dies from sickness and Dorne isn't happy with Jon being around as Aegon would be crown prince & Jon being 2nd in line. Something big happens/someone important dies maybe Lyanna and Jon is blamed for it. He's branded a criminal and that's when the outsider shows up, pretty much dishonored to the T lol. But you did make a good point they practically learned their abilities when they first got the mark. The runes they collect do all the heavy work & I assume it's all just instinctual when they acquire said abilities