This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / A Piece Of Rebellion
Good Cop's Guilt Complex. Since he was the one in control when they touched the Piece, he blames himself for everything that follows. What makes this a full-fledged complex is that it's heavily implied he's conditioned to blame himself for everything that goes wrong, thanks to Lord Business using him as a scapegoat and telling him he's useless.
Bad Cop's inability to admit, despite all evidence, that Lord Business probably won't keep his promise and leave their parents alone. He has to believe that, because admitting otherwise would mean acknowledging that there's nothing they can do to protect their family.
Bad Cop imagines betraying the others and Lord Business welcoming them back with open arms, letting them live happily ever after with their parents.
Good Cop rushes through a bare-bones scenario where he didn't touch the piece and NOTHING BAD HAPPENED THAT'S IT THAT'S THE END GOODBYE.
Emmet imagines giving a big Rousing Speech where he admits to the world how he used to feel like a nobody before President Business gave him his new job, and then Business praises him before they go get tacos together.
Chapter 7 has Unikitty's reaction tothe destruction of Cloud Cuckoo Land, followed by GCBC hearing their parents on the radio and learning just what President Business has planned for them.
Good Cop's panic attack, and the subsequent revelation that he has them once or twice a month.
Wyldstyle and Batman's private argument... which grows so loud the others can hear them from below deck.
Bad Cop's casual reveal that he and Good Cop don't sleep, since that implies they never really get a chance to relax and get away from their issues. They're constantly on-duty. Small wonder Good Cop had a breakdown.
During the same conversation, the revelation that GCBC were put up for adoption by their biological parents. While they're Happily Adopted, again, this does no favors for Good Cop's Guilt Complex: if Ma and Pa Cop hadn't adopted them, Business wouldn't have any reason to threaten them. And Good Cop knows that.
Wyldstyle views Vitruvius allowing her to step up and start leading the group more as her mentor just 'feeling sorry' for her. She also asks Good Cop to do her one small favor: declare that he's the Special. He can't do it.
"I'm fine with this. I've done my job."
Related to the above, when Business erases Bad Cop's face, the mental barriers between him and Good Cop break down. Among his final thoughts? Repressed anger at Good Cop. but it's not his fault it is his fault but I can't let him think that
Emmet's reaction after witnessing Business wiping away Bad Cop's face.
The emotional fallout for Good Cop, and his subsequent confession in Chapter 11 that he entered Lord Business' office expecting to die and completely okay with it. He wanted to die in there, but Bad Cop... he didn't.
Chapter 12 gives us Vitruvius' death and Good Cop being tossed into the Void. Just in case the reader might have been anticipating that turn of events, the Piece is still stuck to his back. Oh, and one of his arms got ripped off first.
In Chapter 13, Vitruvius offers more words of wisdom to Wyldstyle... but she doesn't want to hear it, and calls him out for lying about the prophecy. Even though the chance this is going to be their last conversation before the Think Tank blows up, she's hurting too much to listen, and her last words before his ghost disappears are "I hate you!"
The bittersweet moment after Emmet stops the countdown and frees all the Master Builders. Before any celebrations can properly begin, Wyldstyle notices that Ma and Pa Cop are over by the broken window.
Among all the chaos in Chapter 14, Lord Business notices that Guardbot 189-2001 is among those fighting, and orders for its memory to be completely wiped.
Chapter 15. After hearing The Author admit their own depression, you just want to give them a hug.