(A/N) The prologue to the coming chapters, catching everything up to a certain point so I can start writing. Also spoiler alert, this is going to be one of those, they have to get married for the sake of peace between their realms fics.
He's only ever heard of the sorcerer that resides at the heart of Jotunheim, right beside King Laufey himself. Countless times he had stayed up longer than permitted, squeezing himself between the soldiers of Asgard to listen to their tales of valor before being found by his mother. Always the men tell of how small the sorcerer is and how dark the Jotun's hair is, as black as his heart. Thor doesn't have to wait long before they warriors describe the magic this mysterious Jotun can wield, things that he isn't sure his father could even do. He's heard stories of entire battalions separated from the army by immense walls of ice. There are stories of how the Jotun can shape shift, appearing as an Asgaurdian and then turning back to his hateful form, slaying handfuls of them before disappearing in the blink of an eye. The stories he hated the most were the ones where soldiers died from nothing more than daggers of ice that appeared from nowhere, it angered him that the Jotun would be so sneaky as to kill from afar instead of facing them like man! In all his childish wisdom Thor had once proclaimed he would kill the spell caster when he grew old enough and the men had laughed, obliging to pat him on the shoulder and pander to his gleeful smile.
Sometimes Thor would lie awake in his vast bed and think of Jotunheim, he could only imagine what it would really look like. Once he had sought out pictures of it from the library but had been met with dreary books filled with long passages that only described the terrain. If he learned anything from those musty old books, it was that Jotunheim was nothing but ice made to look like extravagant palaces and the weather could make even the mightiest of warriors shiver. He dreams of standing next to his father, on the shores of Jotunheim, and hearing the cheers of their army when they finally defeat the Jotuns.
For years Thor grew up hearing of the Jotun sorcerer and for years he trained for the day that he would march to Jotunheim and fight against that menace. He gleans as much information as he can when he reaches the age old enough to at least sit with the warriors longer into the night. Centuries pass and the stories he'd hears of Jotunheim waned, become nothing more than border disputes and no longer the full-fledged battles he'd heard of.
Slowly, without his notice, the stories stop and one day hears the news from a servant that there would be talks of a peace treaty between Jotunheim and Asgard. He doesn't know what to feel and when he confronts his father the man confirms it. In a matter of hours his dreams of fighting through the hordes of frost giants are dashed and he is expected to receive both King Laufey and his sons with utmost respect in the next few days.