The soliloquy from Dr Manhattan at the end of Chapter Nine:
Dr. Manhattan: Thermodynamic Miracles... Events with odds against so astronomical they're effectively impossible, like oxygen spontaneously becoming gold. I long to observe such a thing. And yet, in each human coupling, a thousand million sperm vie for a single egg. Multiply those odds by countless generations, against the odds of your ancestors being alive, siring this precise son; that exact daughter... Until your mother loves a man she has every reason to hate, and of that union, of the thousand million children competing for fertilization, it was you, only you, that emerged. To distill so specific a form from that chaos of improbability, like turning air to gold... That is the crowning unlikelihood. The Thermodynamic Miracle.
Laurie: But.. if me, my birth, if that's a Thermodynamic Miracle... I mean, you could say that about anybody in the world.
Dr. Manhattan: Yes. Anybody in the world. But the world is so full of people, so crowded with these miracles, that they become commonplace, and we forget.I forget. We gaze continually at the world, and it grows dull in our perceptions, yet seen from another's vantage point, as if new, it may still take the breath away. Come... dry your eyes, for you are life, rarer than a quark and unpredictable beyond the dreams of Heisenberg; the clay in which the forces that shape all things leave their fingerprints most clearly. Dry your eyes... and let's go home.
Laurie and Daniel falling in love.
Sociopathic Hero Rorschach thanks Nite Owl for being his friend and apologizes for being such a pain.
It's made so much more heartwarming by his awkward phrasing and body language throughout. Even for someone who tends to speak without articles in his sentences, it's clear he's having difficulty saying what he wants to say. And that just makes it so much more powerful when he says it, because it's just as clear that he's not a naturally friendly person, but he's really trying to make a gesture for Dan.
Just as Ozymandias' plan is revealed, we see a group of normal people attempting to stop one stranger from beating another. Two of the people rushing to help are encouraged by the person they're with to just leave it and not interfere in others' problems, but both reject the idea, noting that they refuse to see the pain and troubles of the world and do nothing about it. Of course, the heartwarming moment is interrupted by the horrifying culmination of Ozymandias' plan.
For this troper, the biggest is when the newsstand seller and the comic book reading guy hug seconds before Ozymandias plan is complete; the heartwarming part of this is that those background characters didn't have any meaningful interaction between each other in the previous issues.
Added to when you re-read the comic; not only is the newsstand guy's care for the kid foreshadowed when he gives him his cap and a free comic (despite explicitly stating he doesn't ever do it), but when you combine it with your knowledge of his later shielding of the kid, it only adds to the heartwarming when you realize he really looks out for the kid (despite their squabbles).
My brother thoughtfully suggested that these scenes before all the destruction was a possible refutation to Ozymandias' pessimistic belief that humanity would be doomed to destroy itself without outside intervention.
For this troper, easily the biggest is Nite Owl and Silk Spectre saving a bunch of people from a burning building. An incredible release to see that even in Watchmen's Crapsack World, there's still room for self-proclaimed heroes to perform pure, unambiguous acts of heroism.
Another Rorschach one: When Daniel and Rorschach go to retrieve Rorschach's spare mask, and he calls his landlady a whore to her face. She responds, "Oh, please, don't say that in front of my kids... please, they... they don't know." and he doesn't press it any further. Again, basic human decency for most, but a Crowning Moment for Rorschach.
I think what stops Rorschach in his tracks is the fact that he identifies himself with the children at that point. His mother was a prostitute, he had a miserable life about it. The fact that his landlady's children don't know yet, that they are sheltered from it, is what stops him. His mom being a prostitute, and him being aware, is what contributed him to being Rorschach. By backing down, doesn't Rorschack offer these kids a better life than he had? (They'll find out anyway, but at least it's not him who broke it to them).
Also, as the landlady says this, she is hugging two of her children, trying to comfort them as the scary man confronts her. I somehow doubt Rorcharch's mom was much of a hugger.
For all that Rorschach has deeply, deeply entrenched issues with women (especially sex workers) this scene cuts to the quick, that that's exactly what they are — they're not a proud reasoned part of his philosophical stance, the trauma came first and his philosophy came after.
Rorschach's forebearance is even more striking when you consider that the landlady had been giving the media tabloid-trash lies about him that would infuriate even a normal easy-going person.
After the original Nite Owl has been beaten to death over a case of mistaken identity, Dan is distraught. Rorschach comments impassively that the killing might have something to do with the mysterious deaths of other costumes that have occurred recently. Dan angrily demands why Rorschach can't just let his conspiracy theory lie. Rorschach, still impassive, remarks "Merely suggesting that by finding mask killer, can have revenge for Mason's death. Was meant to comfort you." Okay, it's still a more-than-a-little sociopathic, but considering that it's Rorschach, and that he clearly cares about Dan's feelings and wants to comfort him, it's still strangely heart-warming.
Before that scene, Nite Owl's Berserk Button gets pressed when he is informed of his predecessor's death. When he starts beating up the guy who breaks the news and curses at him, Rorschach (the guy who regularly beats people up at the bar they were in regularly) tells him to calm down, reminding Nite Owl "Not in front of civilians". This kinda shows (aside from a bit of Hypocritical Humor) that Rorschach isn't willing to beat people up for no reason and supposedly has a limit of sorts to his brutality.
Adrian Veidt's Vietnamese servants talking to the interviewer. "He is not one of your pop music stars. He does not inject drugs, or treat young women badly. Make sure you say that."
Probably an odd one, but I always get a little emotional reading Rorschach begging Dr. Manhattan to kill him, because he knows that he if he survives, his nature demands that he expose the truth about Ozymandias' plan.
Or it could be treated as Cassandra Truth, given how outlandish Ozymandias' plan is (Nite-Owl takes a long time to consider its conceivability, even as he sees it in action, and he is arguably the closest to a normal person in this story), and how fractured Rorschach's psyche has become over the years - people could simply write it off as another of his conspiracy theories. Adrian himself points this out after Rorschach leaves.
When Ozymandias says" "I did it. I DID IT!, I saved Earth from hell. Next I'll help her towards Utopia. It is as Rameses said: "Canaan is devestated, Ashkelon is fallen, Gezer is ruined, venoam is reduced to nothing, Israel is desolate and her seed is no more, and Palestine has become a widow for Egypt, all countries are unified and pacified."
Meta-example: While Alan Moore hated the idea of the upcoming prequel Before Watchmen, Dave Gibbons was more open to it. The heartwarming part is that he actually wished them well, and hopes it will be successful.
A little quote from Rorschach (funny how he keeps making it into this entry): "Nothing is hopeless - not while there's life"
In Watchmen, after Dr. Manhattan gives his speech about how miraculous human life is, his ship lands on a giant smiley face on Mars. The fact that there actually is a smiley face on Mars makes it especially heartwarming.
Rorschach's awkward little handshake with Nite Owl, along with his admission that he's a difficult man to know, was so unexpected and nice that it made this troper almost squee.
Rorschach: Daniel... you're a good friend.
Rorschach always refers to someone by either their last name or their costumed name. This lets you know how he has genuine respect & fondness for Dreiberg... or rather, "Daniel".
In his own weird way, Rorschach also shows how he cares about Daniel by preventing him from beating a knot-top to death after hearing that the gang murdered Hollis Mason. He knows that that's not Daniel's way.
The second Silk Spectre's reconciliation with her mother is lovely, the perfect combination of this trope and Tear Jerker.