Despite having only known them for a few minutes at least, Sam almost immediately asks Deadman about the Corpse Disposal team he was with, as well as the Bridge Baby. He may hate being touched, but that doesn't mean that Sam's a heartless person.
Sam vouching for BB-28 after it first gets them through the Beached Things.
"No. We owe the kid our lives. You too."
Episode 3: "Fragile"
Helping the Junk Peddler and the Chiral Artist reunite. They each thought the other was dead, the latter in particular because her mother hated the Junk Peddler and lied. They both grieved needlessly for a year, and as soon as they each learn that the other is alive they eagerly ask Sam to help them reunite. Once they're together, they eagerly agree to get married, with the Junk Peddler even apologizing to Sam for his bad attitude previously. Sadly, if you read the emails they send you afterwards, you learn that shortly after the euphoria of reuniting and getting married wore off, they quickly realized just how incompatible they really are, especially since the Junk Peddler's attitude never really improved. They eventually divorced and the Chiral Artist walked all the back home on her own, preferring to face the harsh environment rather than continue living with the Junk Peddler. Fortunately, Sam gets a few more emails from them in the post-game, which reveal that they eventually got back together and want to try again.
Episode 5: "Mama"
Malingen and Lockne's reunion is primarily a Tear Jerker, as Malingen is dying and barely even has the strength to speak, but they're both still so happy to see each other again. Then, shortly after Malingen's death, we learn that their souls have merged, both now residing in Lockne's body, as demonstrated by Lockne's eyes becoming heterochromatic. Lockne even admits later on that trying to draw a distinction between the two is meaningless, as they have truly become a single entity, whole again.
Episode 13: "Sam Strand"
How the extinction event is averted: Sam (and by extension you) puts down the gun Amelie gave him, runs to her, and hugs her. It is the simplest and most powerful version of what Sam and you have been doing the entire game: Connecting people, and rather than sever another bond with violence and thoughtlessness, Sam, the aphenphosmphobe, puts aside his own issues to connect with the being that is meant to usher the apocalypse.
Sam gets stranded on the Beach after Amelie decides to stave off the Last Stranding. He eventually gets out thanks to the concentrated efforts of his associates at BRIDGES: Mama and Heartman scour the different Beaches for him, Die-Hardman figures out that his gun could be used to track Sam and finally, Fragile teleports Deadman and BB to him, who drag Sam through the Seam back to life. Bonus points when it's later revealed that on the outside, Sam was gone for a month. They really wanted to get him out of there.
Fridge Brilliance: During this whole month, Heartman forewent his search for his family to track down Sam. 30 days of searching, times 60 NDE's a day. 1800 chances to find his wife and child, thrown away to help find The Man Who Delivers. Sam must mean a lot to Heartman if he gave that many chances up to find him. This also adds another layer: for the first time in years, Heartman could do something else but wallow in his particularly hellish grief.
Episode 14: "Lou"
Sam snaps Die-Hardman out of his delirious grief at the end, telling him to own his mistakes as John and drop the masked, unkillable façade and name of "Die-Hardman". Because what America needs right now is someone who is human, not a symbol—and it seems that for the first time in ages, Die-Hardman is feeling a modicum of peace.
Sam feels very strongly that Cliff wouldn't have wanted Die-Hardman to become a man who doesn't fear death—which the last thing America needs with life being as fragile as it is now—and tells him as such. Keep in mind, this is before Sam learns that Cliff was his own father.
Sam and Deadman's final conversation. Deadman affirms himself as Sam's friend by cluing him in on how to get off the grid with Lou; in turn, Sam finally acknowledges their friendship, pulls Deadman into a hug and thanks him for everything.
Deadman is the only person Sam voluntarily hugs. Think about that.
Fragile's reputation has been restored and she begins rebuilding her company as a Bridges-approved subsidiary. She asks Sam to work with her and practically asks him out—he lets her down gently, confirming he's still too traumatized by everything to do more than small steps. But it's clear how much they appreciate each other.
After recovering his own past—an early-era Bridge Baby and Cliff's son—Sam and Cliff reunite briefly and share a hug. Cliff tells him how proud he is of him: that he, a man who only knew how to divide people, brought someone who brings people together into the world.
Lou is holding the quipu-like badge woven from Bridget's umbilical cord and grinning. It's implied that Lou coming back is the woman's silent last act of kindness to Sam.
Sam gave Amelie her Quipu necklace as a gift when he was a child, and she promised to add another knot to it every time she saw him. Since Amelie severed herself and her Beach from the mortal world, and will never see Sam again, she returned his gift to her.
After Lou revives, we pan up to see that a circle of infant BTs have been watching over Sam, implying they were either rooting for Lou to survive, or that they had a hand in helping her (Lou has a very visible chiralium umbilical cord the entire time).
The post-credits shot of Sam once again thinking about the past, but Lou touches his hand to pull him back to the present. Him tenderly whispering her name while holding her hand says it all.
Sam: "Lou... Louise."
The moments of physical affection Sam gives in this episode are especially heartwarming when you remember that he has a fear of physical contact. It would seem this DOOMS sufferer is showing signs of recovery.
Gameplay
If you achive a high enough connection with The Musician, he will give you a harmonica that you can play during down moments in your travels, to Lou's delight. Made even more heartwarming after you find out that it is the same song Cliff used to sing for Sam when he was a BB himself.
The Elder's story. He can die if you don't supply him with medication regularly, but he'll send you one final message before he expires, telling Sam he's glad to have met him and that he agreed to join the UCA - after a lifetime of avoiding it, he felt connected before the end.
In the week leading up to Christmas in Real Life, the NPCs—at the least the ones that greet you when you deliver a package—will all be wearing Santa hats! It's a cute touch that shows some traditions/celebrations, and the spirit thereof, have survived the Death Stranding.
If you go up into the snowy mountains during this time, you can occasionally hear sleigh bells ringing before the ambient sounds start. It seems "the spirit of Christmas' great deliverer [Santa Claus] will always be with you", Porters.
If you exit your private room, you will receive a vision of Cliff wearing a Santa hat and bringing presents to his wife and child, complete with joyful "Ho-ho-ho!"s. He only breaks character regarding his gift to John, his service revolver. After all, Cliff is "done fighting". Doubles as a Tear Jerker.
On Christmas Eve, Sam will receive an email from the BRIDGES team telling him about the holiday. Notably, they describe Santa Claus as a porter for his role in delivering gifts. Then they call Sam their Santa Claus for what he's done for them.
In one of the missions, you help The Mountaineer and his wife, who's going through a difficult labor. Thanks to yours (and The Doctor's) help, she and their baby survive. The new parents decide to name their son "Sam" in your honor.
Even taking into account the general weirdness and total lack of context, Sam clutching the baby tight to his chest like it's the most important thing in the world is an incredibly moving image, and Low Roar's "I'll Keep Coming" playing on top makes it a very beautiful moment. It's a pure, almost primal feeling of (fatherly?) love and devotion.
