Don’t make the secret-keeper a villain. Make them a protector. They are lying to "keep the family together." When the truth finally explodes (and it always does), the betrayal hurts more because the intent was love, not malice.
: Within fan-created content (fanon), "brocest" or similar familial pairings are often used to explore deep emotional subtext between characters who "love each other so much they break the taboo". Fans often look for explicit consent and mutual desire in these non-canonical stories. 2. Characterization of Villainy and Corruption comics family incest best
This is a classic for a reason. One sibling can do no wrong; the other can do no right. But to make this complex, flip the emotional weight. The Golden Child often carries the crushing burden of parental expectation and hidden resentment, while the Scapegoat possesses a painful freedom because they have nothing left to lose. Don’t make the secret-keeper a villain
: Legal or magical "treasures" left in a will can expose long-buried greed and prior family drama. Common Storyline Archetypes Unpacking Family Drama - The Jed Foundation : Within fan-created content (fanon), "brocest" or similar
: Siblings or extended family members clash over a deceased relative's estate, revealing hidden resentments and favoritism. The Burden of Secrets