Because Quinlan wasn't bitten (turned). What you're asking only happends when a human is turned (bitten) by a Strigoi like his birth mother was. Quinlan's mother was bitten by The Master (Quinlan's father in a matter of speaking), so he was changed inside his mother's womb. He was born like this. This is the reason why he's also called "The Born". He's half human half Strigoi. This makes him a hybrid of Human and Strigoi. As far as I know, there's been only five like Quinlan. The race of "The Born". A very special kind of Strigoi. Quinlan's the youngest (he's only two thousand years old, he,he,he) and the last one alive (Well, not anymore :-( ). Not being in control by The Master and being half human make him capable of having feelings like any normal human being (love, hate, sandness, happiness, anger, etc) as he says to Eph in Season 3 chapter 2 or 3 (I think). More proof of this it is previously showed in Season 2 (I don't remember the Chapter) when Quinlan mentions to Gus that Gus' girlfriend is beautiful and that he has also met "Beauty and Love" and has lost both, so he advices Gus to let her go if he really cares for her. This is so romantic! In one of the last episodes of Season 2, Quinlan is sitting with a sad look holding and rubbing his fingers a very old medallion that as far as I know belonged to his late wife. And in another chapter in Season three, when Quinlan meets Dutch for the very first time, he quickly approches to her and looks up and down at her like thinking "She's hot. I like her" But I guess he never tries anything because he doesn't want to end with a broken heart again :-(. But being half Strigoi makes him need blood. He doesn't carry the worms because of his nature. It means he can't turn anyone he feeds off :-) But if he wants, he can kill a living being of blood lost, human or animal. I don't know if you know all his story, but he has many reasons to hate The Master (his creator&father) because The Master tortured and killed his birth mother when Quinlan was very young. He hardly escaped. He also hurt a woman who was like a second mother to Quinlan. He turned Quinlan's wife and adopted daughter. Hundreds of years later, The Master turned another woman Quinlan fall in love with and her daughter who Quinlan cared for (Season 4). The worst part was that in every case Quinlan had to give them a mercy killing breaking Quinlan's heart everytime he had to do it. Poor Quinlan :-(. Anyway, The Master's been a very shitty father to him. Even though what The Master has done to him, he invited Quinlan more than once to join him, but he always said "No" and swore to destroy him. I hope this info is good enough :-). Sorry if I made a mistake, but English is not my first language. I'm from Central Mexico. I've lived most of my life here. I had an American working visa many years ago and I lived in Seattle for nine months. But I always try to do my best to improve my English skills :-) I think Quinlan is very sexy just the way he is =D He's my favorite character on The Strain :-)
