Emma

Emma was an Amazon conceived by Lydia and Dean during a one-night stand, unbeknownst to the latter. After trying to kill Dean, Sam shot her, killing her instantly.

Biography
Born a mere two days after her conception, Emma aged fast, as was customary for Amazons until she reached sixteen years of age whereby the aging process became normal. While still in her crib as a two-year-old, she was able to communicate with her mother by talking. Dean saw her and was confused by the sudden appearance of a baby but was shocked to see her talk with Lydia. Later on, he and Sam learned about Amazons and discovered that Emma was Dean's daughter.

When she grew up to 6 years old in a few hours, her mother sent her away with the Amazon leaders who had her undergo intensive training, including consuming human flesh with milk and being branded with the mark of the Amazons before being sent to kill her father and uncle (since they were threats) to complete her initiation.

Landing on Dean's front door, she tells him that she escaped the Amazons as she didn't want to be what they had planned for her. She tries to enlist Dean's help to stay off their radar. Dean seems to sympathize with her but when she tries to sneak up on him with a dagger in her hand, he turns around with his gun at the ready. She remarks on him being a challenge, as he tells her he was prepared as she tells Dean that he won't be able to kill her but Dean says he can. They converse with Emma remarking on how hard it is for both of them since they're family as Dean tells her she won't get in his head.

Meanwhile, Sam has returned from the professor's office after learning that she was going to kill Dean and is looking through a crack in the door. Sam ran into Remi and Sarah at the door of the hotel. Seeing that Dean was hesitating, he bursts in and Emma turns to face him, flashing him her red eyes before turning to Dean and pleading for his help. However, as she turns again to face Sam, he shoots her in the chest, killing her.