@reika This one is really on the nose because it's more or less actually a thing that happens in FE7 in the B rank support between Eliwood and Hector. Hector has a dream of his and Eliwood's futures and gets comically possessive of a daughter he doesn't actually have yet, yelling at Eliwood he's not going to let his kid take his daughter from him.
Despite that, the two deliberately recreate how they first met- being thrown together by their fathers before a meeting (Technically it was Hector's significantly older half-brother, but for all intents and purposes Uther was more like his father than his brother). It was a minor encounter but it's what started their inseparable friendship and they continued that through Roy and Lilina, who develop a very similar relationship as their respective fathers after being introduced back when they were 5. This gets brought up in both their A support and the epilogue- though the A support is a bit darker with Hector's comments about how he'll never forgive Eliwood if he dies before him, knowing how FE6 pans out