What is the secret of Disgaea Edona?

In "Disgaea", Edona's secret involves her feelings for Krichevskoy (the middle boss, Ladian's father) and her jealousy of Laharu .

Edona initially had admiration and affection for Krichevskoy, but as time went by, she gradually discovered that he had feelings for Laharu. This makes Edona feel jealous and dissatisfied, and she cannot accept that her beloved has a crush on someone else.

In the game, Edona's view of Laharu begins to change when Laharu's mother gives her life to save Laharu. She begins to realize Laharu's pity and vulnerability and decides to protect her. Before the death of the Demon King (Krichevskoy), Edona made an agreement with him to protect Laharu.

However, after Edona's memory was stolen, she forgot about this agreement and poisoned Laharu, hoping to get her memory back. This is one of her great secrets and one of the important plot points in the game.