Durarara!! Episode 2 tells us about a girl named Kamichika. Near the end of the episode, after...
...Celty brings her to the roof to meet Izaya, he lets Kamichika to the roof edge. He tells her that a lot of people have jumped there, trying to persuade her that she's not a special case. After that he leaves, and Kimichika, after some hesitation, decides to jump. However, Celty saves her.
Izaya's motivations here are a little confusing. Even if we forget that he has...
...ordered the kidnapping and rescue of a girl just for the fun of it,
he is being somewhat inconsistent by telling her about all the people who jumped from the roof. At first, it seems like he's helping Kimichika by showing her that her case is neither special nor too bad, and it is not worth jumping. It even seems to work at first, when the girl hesitates. However, when Izaya leaves,
she still decides to jump off the roof!
When Izaya sees Celty helping her, he doesn't act surprised at all, much as if he were expecting this scenario. However, he could neither be sure that
Kimichika would jump nor that Celty would save her (I think he didn't even know that Celty hadn't left).
So does this portray him as a person who knew that Celty would save her, and because of that the girl would once again understand that life's worth living?
Because otherwise he's portrayed as a man who encourages another person to commit suicide just for the fun of observing it!