This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Ramona Quimby
Everything Ramona goes through in Ramona the Pest, since it's shown from her perspective.
The death of Picky-Picky, the family cat in Ramona Forever.
Ramona's Heroic B.S.O.D. after thinking her teacher thinks she's a nuisance in Ramona Quimby, Age 8.
In "Ramona and Her Father," Ramona needs a sheep costume for the church Christmas pageant. Her mother, already stressed, mentions this to Dad when the girls are supposed to be in bed. Dad then says, "We don't want a spoiled brat on our hands," causing Ramona to conclude her father thinks she is one.
In Beezus and Ramona, Beezus, who is nine at the time, experiences real angst over the fact she sometimes does not love Ramona. She assumes this makes her a horrible sister, but fortunately Aunt Bea is there to clear that up.