Charmed universe

 "Melinda, Wyatt, and the Altered Prophecy: Why Piper and Leo's First Child Didn't Meet Their Expectations

In the Charmed universe, the future isn't a straight line, but a river that can change course. One of the most obvious examples of this is the story of Piper and Leo's first child. For years, both the characters and the audience believed that the child would be a girl named Melinda. But in the end, the baby was a boy with unparalleled powers named Wyatt. This change wasn't a plot error, but the result of a series of decisions and events that rewrote fate.
Melinda's Dream: The Original Future

The origin of Melinda's belief comes from the episode ""Morality Bites"" (Season 2, Episode 2). In this episode, the sisters are transported to a future (2009) where they see the consequences of misusing magic for personal gain. In that future, Phoebe is about to be burned alive, Prue has become a cold businesswoman, and Piper has a beautiful daughter named Melinda.

The moment Piper holds her daughter in that future becomes a hopeful image. It plants in Piper's mind and the audience's mind a ""promise"" that after all the battles and pain, she will have a happy family with a daughter. The dream of Melinda becomes the light at the end of the tunnel, the reward for all her sacrifices."