She's cute. She's comic. She's curvaceous. She's Senior Officer Seras Victoria of the Hellsing organization, and the second vampire to join its ranks.
Seras' transformation into a vampire is the point where Hellsing begins. She was the only female in her police unit, and, at 19, the youngest member; her meek ways earned her the nickname "Kitten". Then her unit was sent to deal with a vampire in a village called Cheddar. The rest is history.
So now Alucard is Seras' master, and Seras is a rather reluctant undead. She's the first person to join who didn't grow up with vampires, and she learns about them along with the readers. Her own vampire nature frightens her; she's even hesitant to use that strength to lift her custom-made gun, the massive Harkonnen Cannon. Too bad; it's a very cool weapon.
Seras lives in the Hellsing mansion, which, having already housed Alucard for generations, is able to provide for a vampire's needs. During the day she sleeps in a four-poster coffin; at night she accompanies her fellow Hellsing soldiers on threat-silencing missions. When she's not struggling with her lost humanity, she's a sweet and lovable person who tries to live up to expectations. In her own way, she's as strong as any other member of Hellsing.
In the manga, Seras gets the task of orienting and training the newly hired Wild Geese, led by Pip Bernadette. They have a love-hate relationship which finally settles on love, in the One Canon Pairing of Hellsing. With his help, the police girl will become a key player in the battle for London.