Minor spoilers for revelations.
Rivalries among parents can sometimes take root in their children. Shiro is sure he heard that line in a book he read once. Much like all he hears when mentions of parents come to his ears Shiro was adamant about never making rivals with the same people his father had. What Shiro failed to realize was that it also meant their children as well. So when he finds himself growing more and more competitive with Siegbert.
Siegbert the dutiful and constantly improving son of Xander. A future king just like his father. The young Nohrian could be seen as a direct parallel to Shiro. While Shiro was kept in the dark about his future duties and was not trained for them properly Siegbert was always aware of what his future would be and trained in all aspects of things. Not just defense. Shiro prefers to settle things physically and with competitions a deep desire to win and prove himself, while Siegbert sought to fix things with words and wanted to live up to the standard his father had set.
It was Shiro that told Siegbert he should not compare himself to his father. That Siegbert was his own person and his close friend. The boys had already agreed to keep in contact long after the war ends. Yet, it was also Shiro who constantly wanted to win to surpass his father and prove he could do the job that would one day be required of him. Siegbert had been the first person to ever say Shiro was wise, and was Shiro's first rival despite all the good nature and swears he had made before. As they arm wrestled and departed their way to friendship Siegbert sought to beat Shiro just as much as Shiro sought to stay ahead in this aspect at the very least.
Like their fathers, before them, they were rivals, if they wanted to be or not. Unlike their fathers, they were also friends first. A deep bond forms between the two future leaders, and when Siegbert first sees the person who was supposedly was his grandfather they were forced to lead the charge alongside their fathers and Corrin. It was not Siegbert but Xander and Corrin that delivered the final blow against King Garon. Or the being that had taken over the king.
However, none of the others there knew how deeply that struck within Siegbert. King Garon was his grandfather. A grandfather he never knew but one nonetheless. As well as a former king of the same country he too would rule one day. Yet none of those facts bothered him as much as the fact that Xander was the son of that man, and Siegbert took solace in the understanding of Shiro. As everyone spoke words and truths of that not being the same man he once had been Siegbert could not seem to cope with the fact his father had killed his own father.
When the young prince came to Shiro's dwelling in tears, Shiro was quick to wrap his arms around Siegbert and guide him to the solitude of Shiro's room. No one would dare to try and disturb him there. They sit on the bed as Shiro listens to the woes of Siegbert that was when Shiro a little bit of self-reflection. With tears streaming down the Nohrian face Shiro realizes that he would never know his own grandparents, and in truth that was Garon's fought or the fought of the being that controlled Garon. In truth, Shiro had felt a fire burning against the same man Siegbert held water for. If their feelings were elements that were.
When the other prince finally calmed down enough to dry his face, Shiro found himself changed. No longer did he want to surpass or even to stay ahead of Siegbert. Instead, he found a profound new need to simply walk along his ally hand in hand or fist to fist, whichever way did not matter. As long as he continues to get to be there for him just like he had been tonight.
"You okay now?"
"Y-yeah." Siegbert answers sounding out of breath.
"You know if you feel this way your father and your aunts and uncle probably feel it too. If not worse. I think you should talk to them after this. Or tomorrow."
Siegbert smiles but it was worn and his eyes were still too puffy to match it. "Thanks, Shiro. I-i will, but I just wanted to talk to a friend first. To clear my thoughts and think more orderly before going to anyone else."
"Anytime," Shiro promises offering out his hand. Once Siegbert took hold of it, Shiro pulled him over into a hug. Yes, that fire of rivalry was dead inside him now, but there was another kind burning. Alongside all the other reasons Shiro had to improve and win. It was to make sure all of his friends were okay. Just like what happened tonight.
