The season 2 finale "Black Fire Upon Us" has a big one: Nathan saving Ofdensen from the Masked Assassin and saying "That's my bread and butter you're fucking with."
The entire last 5-10 minutes of the episode.
Nathan also saves Toki, who has passed out drunk, from the fire at Mordhaus, with Toki returning the favor in saving Nathan from Lavona Succuboso. While escaping, Nathan tries to convince Toki to stop binge drinking. Toki tearfully asks if Nathan is telling him this because he cares about him, which Nathan neither confirms nor denies.
In the premier of season 3, Toki and Pickles mourning Ofdensen. Toki keeps a picture of him at all times, and Pickles wears a locket around his neck with a photo in it.
In the season 3 finale "Doublebookedklok", Dethklok becomes despondent and generally messed up when Ofdensen starts putting off time with them in order to organize an upcoming concert in Israel; in particular, Toki is constantly punching the other guys. Eventually the band runs away right in the middle of a tense international situation between Israel and Syria (that they caused), feeling that their manager "finally hates them" and doesn't care about them anymore. Ofdensen takes it upon himself to find them. When he finally catches up with them:
Charles: "I'm sorry I've been so busy, and I see what that's done to all of you. I want you to know you're all very important...to me. And Toki. You don't need to hit people to get their attention. Everybody likes you, thinks you're really cool. ...I think you're really cool."
Toki then jumps up and hugs Charles, who awkwardly comforts him as he breaks down in tears.
The ending, in which Dethklok unites the Middle East. No, seriously.
It starts with tensions extremely high, with war very likely to break out at any moment. One soldier sees something move out of the corner of his eye and turns and takes aim. It's a little girl from the other side...wearing a Dethklok shirt. The soldier lowers his weapon and you can see he also has on a Dethklok shirt, under his fatigues.
It gets even better. If you watch the end credits, one of the clips they show on the news is the soldier with his arm around the little girl.
This troper counts himself as fairly hardened...but every time I see that scene, I tear up. It's also an extremely effective way to show how much Dethklok really does affect the world that they are in.
Pretty much all of Toki's songs are ridiculously adorable, but the one he sings for his cat, along with the lengths he goes to for its funeral, is very sweet.
At the end of "Dethdad", Toki carries his dying father up a steep hill to lay him to rest at the house he was born in (which was his last request) and tells him that he forgives him for all the abuse he put him through.
Toki becoming attached to his guitar tutor in "Dethlessons" and developing a father-and-son bond with him. Right before the elderly man dies in his arms at the end of the episode, he tells Toki "I love ya, boy. I..love..ye..." His grave is then shown, which has a large guitar-shaped tombstone.
Doctor Rockso snapping Toki out of his funk in "Dethzazz". What makes it even more sweet is how it's portrayed - Toki is stuck in a catatonic state where he sees himself as a child again and is being forced to stay in "the punishment hole", a well-like pit that his parents had built. The only thing he had to comfort himself with was a straw doll shaped suspiciously like Doctor Rockso. He imagines a giant spider with his father's face coming towards him...when the doll gets up and banishes the spider with magic powers.
Rockso doll: It's me, your old pal, Doctor Rockso! I could never leave you alone. We're best friends; we're best friends forever...
And though that part may have been a dream sequence, what was real was Rockso coming to get Toki because he refused to have his comeback show without him. For as much of a dick as Rockso can be at times, it's clear he does have some genuine feelings of friendship towards Toki.
The band members may get on each others' nerves, but the moment they find out that bitter ex-member Magnus Hammersmith is a counselor at the rock 'n' roll fantasy camp Toki is attending, they hop into their car and high-tail it over there in case Toki's in trouble.
The real crowner of this episode, and also a pretty awesome moment, is when they arrive at the camp to see that the bullies have smashed the snowglobe that Nathan gave Toki as a gift. Nathan picks it up and immediately goes chasing after the main bully.
Nathan: Oh shit, little kid...you just fucked up real bad.
Also, the fact that Magnus effectively saves Toki's life by giving him a shot of insulin after the bully force-feeds him cake.
On the way to the final concert in Breakupklok, Roy Cornickelson thanks Dethklok for "Making his life better, with their music." It makes his death all that sadder.
In the season four finale "Church of the Black Klok," Nathan's apology to Pickles for taking Abigail and destroying the record.
Nathan: This is the most emotionally brutal thing I have ever experienced.
The final exchange of the season:
Nathan: ...And I'm gonna take care of these motherfuckers, once and for all.
Consider that in previous seasons, the guys have denied having any sort of connection with each other, outside of making music. Compare that to the events of season four, particularly the finale, where Murderface— freaking Murderface— says that after Roy Cornickelson's death, even despite the fact that the band was still technically broken up, the five of them should still stick together.