Sabrina debuts in Chapter 20.
Sabrina is first seen sitting on her hovering Kadabra, watching Red and the Eevee Team Rocket had experimented on leave Celadon City. She is very sinister, saying "good," and then vanishing into thin air.
Additionally, Bill mentions that a nearby gym was attacked by psychic Pokémon recently; this could mean that the Fighting Dojo in Saffron City was a gym, but then Sabrina came in and established her psychic-type gym.
Sabrina creates a psychic barrier around Saffron City, preventing entry and exit. Her Mr. Mime is knocked out through clever teamwork by Red and Blue (instigated by Green). Sabrina catches Green sneaking around in the Silph Co. headquarters and draws her into an illusion.
Sabrina is ultimately tricked and insulted by Green, who manages to break the illusion and escape with Sabrina's Marsh Badge.
She goes after Green and catches her and Red with the Pokémon Badge Energy Amplifier, which Green promptly steals and runs off with. Threatening to kill them, Sabrina sends out Moltres and uses Kadabra's Teleport to bring Zapdos and Articuno. A bright light, originating from the Amplifier, appears and melds the three legendary birds into one, making Sabrina smirk because the time has come.
Sabrina throws an Eevee at Red's feet: the Eevee that Team Rocket experimented on, and later stole back from Red. She reveals that Eevee was the prototype of fusing three Pokémon into one. She also reveals that Team Rocket could have stopped Red and Blue at any time, but chose not to, instead waiting until Red and Blue had collected all of Kanto's badges so that Team Rocket could steal all of them at once to put in the Badge Amplifier. She taunts Red by telling him that Team Rocket will take good care of Pallet Town.
Sabrina and Zapmolcuno fight Red and Blue but lose after Red's Ivysaur evolves into Venasaur and Green regains consciousness (from fainting upon seeing Zapmolcuno). The three cause Zapmolcuno to separate back into Articuno, Moltres, and Zapdos.
Sabrina manages to escape custody.
She uses the "spoons of destiny" at Cerise Island to assign the best partnerships and ends up with Green. The two of them face Lorelei together and end up frozen together, forced to work very closely together. They eventually defeat Lorelei.
Sabrina, injured by Lorelei's ice, goes to Mt. Silver's hot springs, which are known for their curative properties. There she encounters Red and tells him of her sinister predictions for the Pokémon League. When she departs for the Indigo Plateau, she leaves behind a spoon of destiny to guide Red to another, more powerful hot spring.
Like the other former generals of Team Rocket she can be very cold and is seen to be cruel as shown when she tortured an eevee for experimental purposes yet she will help those that she deem worthy as seen when she gives Red directions to a hot springs with strong healing properties. Sabrina is very calculative and is known for her tactics as seen in her gym leader exhibition battle against Bugsy the bug type gym leader of the Azalea Gym. Sabrina is a woman of few words who only speaks when necessary, she also tends to show no outward sense of friendliness or any emotion for that matter, maybe because she sees this as a sign of weakness. Her actions also suggest that she looks down on others unless proven worthy. Her quiet nature makes her a bit antisocial and cold. Sabrina is very composed and cool and her steely nature makes her less susceptible to panic making her the one that usually comes up with a solution as seen in the yellow arc where she decides who will pair up with whom in the battle against the Elite Four using the Spoons of Destiny. Because of her cold nature she usually works in solitude. She may not seem the hero type but in the end she joins the other gym leaders in the battle against the army of masked Team Rocket grunts.
Green was chosen by the spoons of destiny to team up with Sabrina in order to fight Lorelei.