How does 813 develop the theme of Love and Obsession?

813 by Maurice Leblanc develops Love and Obsession across the chapters the companion marks for this theme.

Romantic and possessive love drives many characters, especially Lupin's intense, conflicted feelings for Dolores Kesselbach, which lead to jealousy, violence, and ultimately tragedy, showing how love can become a destructive force.

Lupin's jealousy upon seeing Pierre's love for Dolores drives him to violence, revealing his obsessive and possessive feelings for her.