Have you ever been a fan of a TV series and noticed that after an episode, a character just...disappears?
Like how on Family Matters, the youngest daughter, Judy Winslow, was never seen or mentioned again after being the flower girl at her grandmother's wedding in Season 4.
Or how on Desperate Housewives, Tom's daughter Kayla was sent away to live with her grandparents and the show never mentioned her again.
Maybe you noticed how on Boy Meets World, Topanga had a sister Nebula in Season 1, but then she was completely forgotten about.
Or perhaps it always bothered you how Valerie and Melody (aka The Pussycats) were never seen again after Season 2 of Riverdale.
