The main comic
- Sans and Papyrus being introduced to each other for the first time (when they're mentally toddlers) and becoming fast friends almost instantly.
- One later comic where Gaster, having passed out and forgotten to get himself or the boys anything to eat, makes them perform a "test" which is basically just cooking a meal. The boys get to sit down to eat with him for the first time in their lives. Awkward as the moment was, from then on, even after he's forgotten Gaster, Papyrus loves cooking.
- The moments where Gaster's inner parental feelings break through, such as when he manages to instinctively heal Sans to keep him from dying or when he fights so hard to keep them safe from the goop monster. He rationalizes them away after as him protecting his investments, but it's still something.
- A comic where Sans and Papyrus are ruminating on the old days before the hand plates were drilled into them and they just goofed around and learned things from Gaster while he did his work. It not only makes all the silly fluffy comics about that time canon (well sort of, Zarla has admitted that the exact events depicted probably didn't happen) but it also shows two moments where Gaster genuinely smiled at them: once when Papyrus childishly comforts him over something, and once when Sans impressed him with his intelligence. It's heartwarming even if in a retroactive, sad way.Papyrus: Do you think he misses us?
- Following Gaster getting erased, it feels very sweet and a long time coming when thanks to Asgore, Sans and Papyrus figure out what their names should be based on their fonts. They're not just "subject 1" or "subject 2" anymore.
- The arc where Sans and Papyrus finally make it to Snowdin and settle down in what is presumably Gaster's old house, and Sans admits that they're finally happy. The panels are a reference to an old comic where Papyrus uses his future sight and see themselves outside of the lab, and they take hope from it that one day they'll escape. They were right.
- Sans meeting Alphys for the second time, not that either of them remember that in the dump. She ends up offering her help finding things and immediately starts calling herself stupid for thinking he'd need it. Sans gives her a line by asking if she knows where some car stuff and cellphones are, and the happy look on Alphys' face is really sweet.
Mercyplates AU comics
- One of the Mercyplates comics that has Gaster giving up the experiments after the "beam" incident. Gaster finally gives Papyrus corrective lenses (alluding back to how he suspected Papyrus had bad eyes in the main comic) and Papyrus is just so ecstatic to be able to see clearly, even if Sans is suspicious of Gaster the whole time.
Gaster: You are... a good person. That's more than most of us can say.
- In a comic directly following that one, Gaster gives Papyrus validation for his willingness to forgive him despite all he's done. Papyrus is overjoyed and hugs him, and (albeit after being chastised) Gaster even hugs him back. It's the most affection he's ever shown to Papyrus, after spending so much effort refusing to get attached.
- A Mercyplates comic where Gaster gave up the experiments when the boys were still babies. He's sitting there worrying about the future and how he's made every problem he has even worse by making the boys, and then Sans starts rattling and he's floored by how cute it is.