Josefina now known as Dr. Deborah Santos is part of a monstrous race known as the Manananggal, more specifically of the Tik-tik variation. These types of manananggal not only deploy bat-like wings and hover without their lower bodies but also have a penchant for extracting human fetuses from pregnant women. Deborah, being a doctor, has her work cut out for her, in that she can easily find prey among the women she 'tends' to. However, she holds the secret to Carding's past.
Josefina was always fully aware of her family legacy, that is of the Manananggal race. She frequently got into arguments with her mother because she would not accept that she too was a Manananggal. She lived in a mansion with her mother and her baby. Josefina always refused meals of hearts and fetuses, part of the palate of the Manananggal. Her mother reiterated that nothing she did would make her a normal woman, not even studying medicine.
One day, the townspeople attacked their home with spears and torches. Josefina tasked her nanny Marina to take her baby to safety. She then found her mother dying on the stairwell, telling her she cannot escape her destiny. Enraged with what the townspeople had done, her demonic side steps in and she retaliates against the townspeople who atatcked.
Flash forward many years later, as Deborah, she serves as a maternal doctor in San Martin. In her mind she swears that the Manananggal will keep killing until she finds her child who revealed to be Darna's sidekick, Carding. It remains to be seen if her son has monstrous powers inherited from his mother.
In San Martin, many pregnant women fall prey to the manananggal, prompting Pancho andNarda to investigate in each other's own way. Narda begins to wonder if the new doctor has any connection to the killings. Deborah eventually meets Ding and, through a tear in his shirt, she discovers he bears the birthmark of her child. Deborah attempts to get closer to Ding but Narda, already suspicious, gets in her way. Deborah begins to plan how she can dispose of Narda. She kills Narda's pregnant friend Gina, and leaves Narda to find her. As the townspeople come upon the scene, Deborah accuses Narda publicly of being the Manananggal. The two have a verbal throwdown where Narda implies Deborah is the manananggal. The public are divided on who to believe but Ding speaks up and tells Deborah to stop accusing Narda. Taking a cue from her son, she ceases.
Deborah eventually confesses to Ding that she is his mother. Ding is apprehensive but decides to accept her. In a strange turn of events, Vladimir attacks Ding which brought out Deborah's dark side. As Deborah throws down with Vladimir to defend Ding, Ding discovers she is the Manananggal. Later on, Ding shuns Deborah and begins fearing that he has his own dark side. However, as Black Rider finds Deborah and threatens her, Ding comes to her rescue. Narda tells Black Rider that she'll handle Deborah. Narda tells Deborah that more than anything, he's in need of a mother. It is then revealed that practically all of Deborah's transformations are involuntary and caused by distress or anger.
After his encounter with Deborah, Eduardo (Black Rider's secret identity) tells Watson the identity of the Manananggal. Watson later does surveillance for Eduardo and doesn't manage to control himself, telling Deborah's suspicious landlord that Deborah is, in fact, a monster. Later that night, at one point Deborah nearly becomes the manananggal but manages to stop her transformation, however, it may be too late, as the villagers now know about her secret.