Lyn's reunion with her grandfather at the end of her tale. Hausen's reaction, Lyn's assertion that despite taking so much poison he'll recover, and the CG of them embracing is, in this troper's opinion, one of the most heartwarming moments in the game. Also a bit of a Tear Jerker.
Gonzales' epilogue in Sword of Seals. Being recognized as a hero from a place where he was originally viewed as a brigand who would sack towns. All because Lilina saw that he was not a bad person at heart.
Dorcas and Farina's supports in FE 7. Dorcas's wife has a bum leg and Dorcas works to earn money for her treatments, and when Farina finds out she gives him this huge sum of money. These supports are among the best for revealing Farina's Hidden Depths.
Hawkeye's supports with Ninian provide some information about Arcadia, a hidden paradise where dragons and humans live in peace together. At the end of their A support, he tells her he has hope for a future where all of Elibe can be just like Arcadia, and Ninian says she believes this as well.
Anything involving Nino and Jaffar, from when she saves him out of compassion to his Declaration of Protection to her, and his going out of the way to lay it hard on Sonia. Their support conversations take it Up to Eleven with Love Redeems in full force.