This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Spinnerette
Every time Mecha Maid's ALS is brought up, particularly when she reveals that it's progressing faster. On a related note, Mecha Maid revealing that, because of it, romance was never really a possibility for her.
When Tiger learns of a school shooting he is initially afraid his daughters got hurt, and when he is overjoyed they're safe they point out someone else lost their daughters that day.
This page, and Heather's many conflicting emotions—including "I'm sorry I walked away I'm sorry I hurt you", "I'm scared", and in the corner, a tiny, little, backwards "Maybe I love you too." Someone give the poor girl a hug.
The death of White Heron.
When Glass learns that the breeding camps and experiments left Mecha Maid paralyzed, he seems honestly regretful about it, and has a Pet the Dog moment by leaving Mecha Maid alive and telling her to spend her remaining time with her loved ones.
After three pages of trying and failing to push Heather away out of guilt, Marilyn admits that she intended to commit suicide through fighting Glass, before finally and understandably breaking down sobbing in Heather's arms.