This kind of fanfiction usually involves fictional and imaginative scenarios exploring romantic or sexual relationships among these characters. However, it might vary greatly depending on the author's creativity and preferences.
In ancient times, a copper coin was worth one coin. In ancient China, coins were divided into different characters, such as Wen, Wu, Xuan, Huan, Bao, etc. Each character represented different values and uses. The word "Wen" represented the face value of the copper coin. And "one point" referred to one hundredth, which was usually used to indicate the weight or volume of small items. Therefore, in ancient times, a copper coin was worth one coin.
One possible plot could be that Percy has finally had enough of the gods' interference in his life and the lives of his friends. He might yell at them for their unfair treatment, like how they often use demigods as pawns in their games. Maybe he'll demand more respect for the sacrifices demigods make.
Some fanfictions where Draco yells at Harry are often centered around their complex relationship. In a story like 'The Rift', Draco yells at Harry because he feels betrayed. Harry might have made a decision that affected Draco or his family in a negative way. Also, in 'Shadow of the Past', Draco's yelling could be a way to cover up his own insecurities. He yells at Harry as a defense mechanism, when in fact he is struggling with his own identity and place in the wizarding world after the war.
Penny is the person whose story is being told in 'my 600 pound life penny's story'. She is probably a person who has been struggling with her weight, which has reached a significant amount, likely 600 pounds. Her story may cover various aspects of her life, including how she got to this weight, her daily challenges, and her attempts to change her situation.
It basically means that every penny you save is as valuable as earning one. In a story, it might show the importance of being frugal and careful with money.