The most violent psychopath serial killers are usually the most charming and friendly people at first, thats why they are so successful at luring girls to be their victims.
If girls continue with a random guy who talks to them on the train, bus, street whatever; first they are completely head over heels with his charm, friendliness and romantic flirtatious comments about how beautiful and elegant she is. After falling instantly in love with him, he invites her over to his apartment for a drink.
Along the way he treats her like the perfect kind gentleman.
Once she walks in through his door he smashes her over the head with the bottle of French wine he bought for her. As she lays half conscious he ties up her hands and legs with rope and wraps several layers of duct tape over her mouth to stop her from screaming.
As tears pour down her face he drags her into his basement where no one will hear anything. He rips off her clothes and brutally rapes her repeatedly over a period of several days. Also physically torturing her with sharp objects.
Once he has had enough he murders her and cuts her body into tiny pieces and puts them into a garbage bag. In the middle of the night he drags her remains into the woods where she will never be found and buries her body with lime to help with the decomposition. The next day he goes back to the train station to find another victim.
So remember girls, the next time that charming, handsome guy on the train comes up to you and tries to chat you up, you could end up as worm food in the woods if you wanna keep talking to him.