WARNING! MASSIVE SPOILERS!! Lucina reveals herself to Chrom as his daughter and begins crying. As he wipes the tears from her face, shes runs into his arms and cries on his shoulder. All the fans hearts melted. Also counts as a Tear Jerker.
Following that is Lucina's reunion with her mother.
In Yarne's supports with her they both vow to protect each other. Yarne realizes how alike they are, both taking blows to protect the other, and in their S support, he asks her out, as he wants to keep her safe forever. Doubly impressive, considering she's royalty.
The supports between Henry and Olivia, also include a little Tear Jerking, as we learn about Henry's childhood.
Hell, almost every support with Henry is a mix of heartwarming and tear jerker. No joke. With Cherche, he becomes friendly with her and Minerva, nearly getting his hand bit off alone in rank C. In rank B, we learn Minerva reminds him of a Giant Wolf that became his only family in perception because his mother and father were such terrible people to him. The Giant Wolf one day visited him in his village, and was shot to death where she stood by the hunters. He then made them pay.
On a separate note, Henry and Lissa's Supports involve Lissa losing sleep because she's worrying not only about her allies dying, but also her enemies. Henry then uses a curse on her (the nonlethal version) so she can fall asleep. When she asks about how he did it, it turns out he has to do a fresh sacrifice, and usually uses little birdies. The heartwarming is after she tells him to stop doing it, not only does he stop using birds for sacrifices, but she falls asleep on him, and at the beginning of the S rank, turns out she's been using him as a human pillow.
Also Henry and Sumia's supports. In the C one, she's berating herself for her clumsiness but Henry doesn't seem to mind that much and helps her via temporarily fixing the stuff she broke so she can replace it. In the B one he explains how he uses his curses for daily things and offers to help her learning magic. In the A one they switch bodies and they're kinda weirded out when back to normal, but in the S one it turns out they did it again... so Henry could ride her Pegasus without being rejected by it — and this is followed by their love confession in which Henry starts saying he believes Sumia is actually an Ill Girl since, when in her body, Henry-as-Sumia's heart raced so fast... but after talking a bit more, they see the same happened viceversa (to Sumia in Henry's body), so yup, they're in love. And to crown it, he adds that when in Sumia's body, he brought her an engagement ring. Which is the other reason why he asked for a second body switch.
Sumia: "You've cast the best hex of all... And I couldn't be happier!"
All the S supports between characters have elements of this, but those between the Avatar and another character are particularly touching.
In a male Avatar's S-Rank with Sumia, she gives up on the escapist reading to improve herself. When Avatar offers her a ring but admits he can't give her status or a fairy-tale romance, she says it already is one for her.
Vaike has a ring prepared for the Avatar, but this being Vaike, he loses it. He frantically searches for it, and the Avatar catching his sketchy behavior doesn't make it any easier. Cue Sully's terrifying horse, who has been been out to get him for peeping on the women in the army bathing the entire support, finding the ring for him and nuzzling the Avatar.
The supports between the Avatar and Emmeryn may taste like diabetes, but everyone agrees they're this, especially given their relationship's ending.
Her conversation with Gangrel in Hot Spring Scramble also qualifies.
ALL parent/child supports, as well as the scenes between parents and children in their recruitment sidequests.
Cynthia has one with her father where she admits her being clingy with him is because she understands time travel and realizes that he will eventually have her present counter part that won't be her and she is willing to accept not being around during that time as long as they are able to forge memories now that both she and he can always keep.
Lissa and Owain's stand out too, especially when she glomps him for being such a caring son in both B and A.
For this troper, there's just something to how she immediately takes to being called "mother" and calls her son "sweetie" and the like.
Morgan's support with his/her non-Avatar parent end with him/her recalling only a very vague memory of their father/mother smiling at them and calling their name, but it's enough for Morgan, and their parent promises to always be there for them.
Laurent is identical to his mother in many ways, including coming off as emotionless and feeling the need to be mature. His A support with his father proves that he does have a facade, and the fact that he came from the future to the present first and spent all of his time alone for five years has made him afraid of possibly going crazy. Cue his father comforting him as Laurent breaks down.
Adding to that is the fact that it's one of Laurent's only conversations when he speaks normally, as opposed to the more meticulous speech his mother uses.
Pair Up two characters who are married, or parent and child, and have them step on an event tile. Prepare to have your heart melted.
Even better, pair up a unit with his or her spouse and view either of the couple's portrait in the in-battle animations (by tapping their character portrait on the touch screen), he or she will be blushing!
After completing Chapter 10, Chrom begins to suffer a Heroic BSOD in the aftermath of Emmeryn's death. The Avatar assures Chrom that he/she will help him through whatever trials he will have to go through, followed by everyone giving their own words of encouragement to him, culminating with Chrom thanking everyone for their support.
And what happens afterwards? It's revealed Emmeryn's death caused many of the Plegian soldiers to desert, tired of all the violence.
In the Final Chapter of the game, the Avatar can opt to pull a Heroic Sacrifice where he/she does a "I'm Taking You with Me" on Grima since you are both one in the same. This guarantees that Grima doesn't come back again at the cost of your own existence. Chrom and the surviving members of your team all refuse to believe you're dead and plan on searching to ends of the earth until they find you.
After the credits and "THE END" screen pop up, the game goes into another CG sequence of Chrom and Lissa finding you in a field, just like in the prologue... but this time, the Mark of Grima is gone from your hand and after pulling you up, Chrom says "Welcome back. It's over now."
If the Avatar is married, the notes on how he/she went on to live her life his/her life after returning state that the Avatar's origins and past are still unconfirmed and contested, but that one thing is for sure: He/she loved his/her spouse dearly.
If the player chooses to let Chrom make the final blow, this spares the Avatar but will also allow Grima to return Back from the Dead one day in the future. The Avatar will feel guilty because of this. However, his/her spouse and kids will remind him/her that he/she still got a family.
Lucina's supports with a Male Avatar, in which he continually goes out of his way to ensure she's not overworking herself and remind her that she is not alone.
Lucina's support conversations with her parents. ALL OF THEM!
Her A rank support with her sibling will also make you go all "D'AAAAAAW!"
Say what you will about Tharja, her A support with Ricken falls into this when he hits her with a happiness-contagion curse and makes comments about how pretty her smile is. It's also one of the only support lines that doesn't have her make a single comment about the Avatar.
Kellam is another one, and this one shows she surprisingly cares about her family a lot, and actually uses her magic in a non-malicious way (for once) to help Kellam's family take more notice of him. Despite her creepier habits, when Tharja's Hidden Heart of Gold comes out, it really shows.
A lot of Tharja's supports actually show her being a good person deep down. With Virion, she thinks her mind controlling curse worked, and she makes Virion do charitable things like building a bridge or repairing their comrades' tents so they're dry when it rains. The twist is that Virion actually wasn't under her control, and he was just doing those things because he likes her, so it's a double crowning moment of heartwarming.
Tiki's voice actor for whenever she says "Mar-Mar" absolutely nailed it to show just how much she really loved him just by speaking his name.
The Avatar's ending if he/she is married. Though accounts wildly differed of what s/he acted or even looked like, the one thing everyone could agree on was that the Avatar loved his/her spouse above all else.
According to Owain, his father gave his life to protect him from an archer that ambushed him. Ever since then, Owain constantly brags about the blood of heroes that flows in him: the blood of Lissa's ancestors, and the blood of his father. That's right, he loves his dad so much, he regards him with the same amount of renown and respect as MARTH.
It gets an extra level of "d'aww" if Lon'qu is Owain's father, given that Lon'qu's supports with Lissa see him take an arrow for her during an assassin ambush.
It also gets some extra heartwarming if a male Robin is Owain's father. Despite Robin becoming Grima in Owain's timeline, Owain still considers Robin equal to his mother's bloodline.
Cherche telling Lon'qu that the parents of his late friend Ke'ri wanted to thank him for giving their daughter happiness with their friendship, when he thought that they hated him for failing to save her.
In Rogues & Redeemers 1, if you have Tiki talk to Marth, he won't recognize her. But he will say she somehow reminds him of someone very close to him.
If you visit the barracks on your avatar's birthday, all of the characters' will wish you a happy birthday instead of normal messages. Even characters like Lon'qu, Severa, and Walhart.
It's made more heartwarming when you realized the characters' happy/cheerful portraits are used. Standard barrack messages are always accompanied by the characters' default portraits.
Kellam's love confession to the female Avatar is the cutest thing ever:
"You make me feel like I-I'm really here. Like I mean something. I am yours... forever.”
In Yarne & Nah's A support, Yarne rescues Nah from skirmishers who took her by surprise. Their S support has them dealing with the aftermath of the ambush, where it's revealed that Nah has had trouble sleeping, she's so traumatized. Yarne, a self-admitted coward, swears to stand guard by Nah's tent and keep her from ever getting kidnapped again, and confesses that he'd fight anyone just to keep her safe. Nah declares him a hero, and seems to hug him in the final scene.
Chrom and the female avatar's conversations when they're married to each other in Summer Scramble. In the first part, Chrom notices how much the avatar is enjoying being at the beach, but she accidentally lets it slip that she's bothered that she doesn't have her memories from before she met Chrom. She tells Chrom not to worry about it, then runs off to check something out. Chrom then decides that he'd do something for her while they're there to cheer her up. In the second part, the female avatar comes across Chrom and a pile of broken seashells (he says he was trying to make a necklace, and that he has "a talent for smashing things in frustration"), some charred lumps that he says were his failed attempts at cooking fish, a collapsed sand castle, a half-built raft, and a "bug-infested tropical fruit salad." The female avatar tells him to save the beach activities until after the battle, but he shows her one more thing: a big message in the sand that says "Chrom & [Avatar] 4 Ever." Chrom asks if it made her happy, and the avatar lampshades the Narm Charm and says that she's not sure if she "should be happy or embarassed or...what, exactly..." but says that it's still certainly a sight she'll never forget. Chrom then reveals why he did all this: he wanted to help her make new memories. The avatar thanks him, and tells him that he didn't need to do all this and says that just being with him has given her "an endless supply of happy memories!" She recalls all of the happy memories that she has with him and says that she could never forget a single thing about him, even if death were to tear them apart or if she lost her memories again. Chrom then gets onto her for talking about such sad situations and gives her a "Shut Up" Kiss so she'll stop talking about such sad things! She chides him for doing something like that in the middle of a battle (though does admit it was wonderful) and tells him to stay in his position and continue fighting, and she runs off to rejoin the battle. She then says to herself that while it was ridiculous for him to do something like that in the midst of battle, at least he gave her one more memory she'll never forget.
Every character which is focused on (Chrom, Gaius, Tharja, Cordelia) could be added. For example, in Cordelia's conversation with a spouse Avatar starts off with Cordelia collecting pretty looking shells. The Avatar stops by, concerned that she was injured, when in reality she was picking up a shell off the beach, which the Avatar buys. Only after that does the Avatar even notice the pile of shells behind her. He's convinced by Cordelia that the shells were placed there by bandits and she moves them to a different location. In the second conversation, Cordelia has found the time to decorate all of her lances with her collected shells. The Avatar asks what she's doing with her lances...and she claims she was testing a new lance design, showcasing it by throwing one of them a far distances. Impressed, the Avatar decides to try out another lance before Cordelia stops him, claiming it's her favourite, admitting that she's been spending the day decorating while everyone is off fighting, and stating that the Avatar has to be disappointed in her and she'd be fine if he wanted to annul the marriage. The Avatar instead finds it refreshing that Cordelia actually has hobbies and relaxes...and begins teasing her. Being teased is a sore point for her and she charges the Avatar beating the Avatar and kissing him in front of the whole army. The Avatar is flustered, to which Cordelia suggests he plan a surprise romantic suggestion if it's bothersome to him, and that she'll be watching him...and only him. What's amazing is that they cover so many of Cordelia's personality points: her competitiveness and low self-esteem in particular.
The Avatar and Lucina's spouse conversations in the Hot Springs Scramble DLC. The first part is relatively lighthearted, with Lucina empathizing with a fellow newlywed couple there and embarrassing each other asking the Avatar about the mixed bath. The second part is a bit heavier, with Lucina questioning whether she will be able to stay with the Avatar after the war is over (due to her status as a time traveler and his status as Chrom's tactician) and berates herself for not being able to put the Avatar before her mission. The Avatar responds by saying that she has every right to put saving the world first and that he will always stay with her no matter what she does. He even goes so far as to say that he'll find a way to come back from the dead if he dies. He plants a kiss on her and after he leaves to continue fighting, Lucina apologizes to the Avatar for the situation they are in and notes that he is the most important thing to her in the world, and her primary reason for ending the war is so that she can be with him. Considering how important her father Chrom is to her, the fact that she would consider the Avatar to be even more important is profound.
If a female Avatar married Owain, there's quite a blend of lighthearted and touching during their conversation in Hot-Springs Scramble. It starts with humor (considering the spouse, it's not surprising) and an adorable realization they don't know that much about one another. Then it shifts to a sadder tone when the Avatar admits her fear of forgetting the time she's spent with him and everything she has done like she had for her childhood memories. To comfort her, Owain gives her both a Cooldown Hug and a mild "Shut Up" Kiss on top of it. He reassures the Avatar that he'll stay by her side to keep those memories and remind her if she forgets, not matter how many times he may have to. The icing on the cake is the Avatar borrowing Owain's style of speaking when she's alone to monologue her happiness with him.
Inigo's conversation with the Avatar if he's married to her is also heartwarming. The Avatar's getting a little annoyed with how affectionate he is when they have to battle Risen. But when she think he's overdoing it with the closeness, he's actually taking a hit for her from a Risen targeting her. It's the one instance where the Avatar is crying, because she thinks she failed as a tactician to have him get hurt for her mistake.
The Hot Spring Scramble conversation between a Male Avatar married to Severa is also rather sweet in its own way. It starts off with Severa planning on using the trip as a honeymoon for the two of them, and she demands that he make plans for it. During the second part of the conversation, he says that he hasn't had much time to think about it with all the fighting going on and Severa understands, but takes a peek at the paper he's holding, thinking it's some new tactics for them. It's actually his ideas for their honeymoon. The prickly Severa is clearly moved to tears and opens up a little.
Robin (M)'s father-son supports with Owain in Hot Spring Scramble. Owain belittles himself for not being more like Chrom or Lucina, to which Robin responds that he's very proud to be Owain's father.
Male Robin and Kellam's A class support, where its revealed that the group is throwing a party for Kellam to remind him that they know he's there with them and they count on him despite what he thinks.
Hot Spring Scramble is CMOH incarnate. Two in particular are Emmeryn's conversations with Chrom and Lissa. As implausible as her survival is, it's clear that her younger siblings are grateful to have her back, even in the condition she is.
Also joining Emmeryn's Hot Springs conversations is Gangrel, who nearly crosses the Despair Event Horizon as he dwells on what he did for the first part of the game. Emmeryn decides to comfort him, despite his apprehensiveness to approach her, as he was the one who demanded her execution and drove her to the current state she was in.
"How in blazes did you get me to...love you? If you're trying to make a new man of me, it's...working..."
Cordelia proposing to Gregor in their S support. Keep in mind Cordelia's feelings for Chrom, Gregor thinking she could never feel that way for him, and that he was trying to help her win Chrom's heart. His tips worked...in Gregor's favor!
Cordelia: "I propose to Gregor!"
Actually, any of Cordelia's S supports where she proves that even if she'll never forget her first great love, she can love someone else and be happy with him.
Yen'fay and Say'ri's conversation in Hot Spring Scramble. After the way their conversation goes in the Paralogue where he's recruited, Yen'faycomforts Say'ri when their reminiscing reminds her that he isn't the same brother she knew and assures her that he does care for her.
If Lon'qu is Inigo's father, their conversation in The Future Past 2 doesn't start this way, but it definitely ends that way. Inigo assumes that Lon'qu has come from the afterlife to collect Inigo's soul. When Inigo tells Lon'qu as much and admits that he (Inigo) is finished, this conversation happens:
Lon'qu: ...Finished, you say? If you're that ready to die, I won't bother with any speeches.
Lon'qu: Inigo... I sentence you to death here and now... Prepare to die.
Inigo: Ack! Wait!
Lon'qu: What's the matter? Come at me. I'll make it painless for you.
Olivia and Inigo's A support is both heartwarming and a tear jerker. In the future, Olivia was teaching Inigo her favorite dance, but died before she could teach him the last half. Inigo would then practice the dance by Olivia's grave, making up his own ending to the dance and wondering what his mom would say as he practiced. Now that Inigo has his mother back, he can finally show her the dance he put together in her memory.
Nah's supports with male!Morgan, particularly the A support, where he risks his life to find a super-rare flower just for her. The S support also stands out, for being her only romantic support where she confesses her love, and for this bit:
Morgan: You had a second wish? What was it?
Nah: ...for the person I love to love me back. But there's no need to ask Naga, because he cared for me all along.
They may end up on the end of generic parent supports, but the fact that some of the male characters with less than happy pasts concerning family like Henry (neglected and raised by a wolf), Lon'qu (grew up on the streets), and Libra (straight up abandoned), embrace becoming parents (and caring ones at that) is enough to make anyone's heart melt.
Cherche and Gregor's supports reveal that they have a connection neither knew about. Years ago, Gregor was hired into a group to collect wyvern horns, but the rest of his group decided to speed things up by hunting wyverns down instead of finding ones that were already dead. After the hunters killed a mother wyvern and threatened her baby, Gregor turned on them and saved the baby wyvern. Years later, that baby would turn out to be Cherche's mount, Minerva.
Lissa and Maribelle's A support, in which they discuss why Maribelle is so completely devoted to Lissa. Despite being nobility, Maribelle's overall temperament and sharp tongue made her a friendless outcast until Lissa approached her and offered to be friends. Lissa doesn't even think it was anything special, just that the other kids were jerks and that a great person like Maribelle didn't deserve to be treated like that.
Tharja and Libra's ending. If they get married, their new future has them founding an orphanage and living happily together. Tharja apparently learns to control her cursing tendencies as the children there come to adore her, and she secretly liked the attention. If Noire goes unmarried, then she joins them, but not to protect her past self, as Tharja doesn't wind up as the heart widow she was in Noire's original childhood. She joins them in order to live a happy life with her parents.
Their support conversations are heartwarming, too. It's quite sweet to see Tharja slip into mix between Adorkable and Tsundere when Libra confesses his love for her by letting her look into his heart. And while she's still mostly interested in her experiments in their A support, there's this hint of fondness in her words, if ever so subtle. Not to mention, of course, that her experiments on Libra has blunted the pain of his past that has burdened him for so long.
If Brady goes unmarried, his future has him becoming a world-renowned violinist, famous for his music being so beautiful and melancholy that it would bring all those who heard it to tears.
And all of his paired endings (except with Morgan) involve his wife having some sort of connection to his music. Kjelle stands out, learning music and performing duets with him, because she always wants a new challenge.
If Gregor and Nowi are married, then Gregor enjoys a life of plenty for a time, but then travels the world with Nowi.
In Tiki's ending, she returns to her duties as the Voice, but now comes down from her perch and visits the people more often.
Tharja's entire S support with Lon'qu. After their plan to simply remove his traumatic memories didn't work out, he tries to get close to her and overcome his fears through "tyranny of will". She notes that this method would probably take years and asks if he will let her help him. Not through magic or tricks, but through friendship and companionship, being together day and night. When Lon'qu pretends he still doesn't get it, Tharja outright proposes to him. Lon'qu accepts and offers her a ring...
Tharja: ... Wait. You had this ready the whole time? (smiling) Oh, you are a sly dog, Lon'qu.
Female Avatar pulls one of these when she sees that he is standing alone with Lucina for the first time. While shedoes still point out (correctly) that the married Exalt standing alone with a beautiful, crying woman is how ill rumours are born, the very next thing she says is that she trusts him. It's a nice touch, especially when you know how the other conversations go, and it goes a long way to show just how much faith and trust the Avatar and Chrom really do have in each other, both as friends and as husband and wife.
Panne and Libra's supports. All of them have Libra realising that for all Panne's cold attitude, she really does care about others. Their A Support has Libra finding out that Panne beat up some soldiers that were making 'off-colour' comments about him. Panne tries to brush this off - "Maybe I just wanted to hit someone that day" - but admits that she was angered by the comments after her conversations with Libra made her feel better. Libra is amazed at the kindness she shows, though she tries to hide it, no matter what the world throws at her.
Whether you ship it or not, Sumia rescuing Chrom is one of the sweeter scenes in the game.
Frederick's confession of love to Sumia is tooth-rotting glurge, yeah, but it's so geniune. He admits at first he kept an eye on her due to her clumsiness, but as time went on he began to see her as a wonderful person he truly wanted to know...and love. Sumia's acceptance of his proposal is pretty sweet, too:
I don't want the moon, Frederick. I just want you! So yes! Yes and yes and yes again! You've made me the happiest woman alive!