If Not "Siblings"

At the age of sixteen or seventeen, a pair of siblings live in poverty, and a boy suddenly breaks into their lives. The emotions of these three people are intertwined and staged farce after series, and at the same time they lead to the mystery of the younger brother's life experience. After all, how should they face life and how should they face emotional choices? Please pay attention to this book and give me your valuable opinions. Note: The plot of this book is purely fictitious and any similarity is purely coincidental.