Welcome to the Master Plan

Also, further notes on the hilarity that is Izaya's name (obtained here):

Orihara is not too uncommon a surname - Narita probably wished to stress his ordinary origins here. The kanji for Izaya's given name, a very rare combination if ever used at all, would usually be pronounced Rinya and definitely not Izaya. And it seems that 臨, when used singly in a male name (a rare instance as well), is usually pronounced Nozomu.

The only reason his name is pronounced Izaya was that his parents wanted it to sound the same as the biblical prophet Isaiah (phonetically Izaya in Japanese). When Narita first introduced Izaya he mentioned another origin of his name - 臨 is also a reference to the phrase 臨む者, which could mean -the one who rules- but also multiple other things depending on the context, e.g. in the following biblical quote:

地の上に空な事が行われている。すなわち、義人であって、悪人に臨むべき事が、その身に臨む者がある。また、悪人であって、義人に臨むべき事が、その身に臨む者がある。わたしは言った、これもまた空であると。 －伝道の書 8:14

There is a vanity which is done on the earth, that there are righteous men to whom it happens according to the work of the wicked. Again, there are wicked men to whom it happens according to the work of the righteous. I said that this also is vanity. - Ecclesiastes 8:14

... in other words, lol. Izaya's parents.



In the novels, Izaya actually believes Shinra sums him up best.

Orihara Izaya was not an "otherworldly" being like Celty nor an ultra-mighty warrior like Heiwajima Shizuo; he was but an ordinary human.

He was not completely rational and calm like a robot or a cold-blooded creature that didn't feel a thing about killing.

He was a human through and through.

Harboring desires ordinary humans too would harbor, crossing lines ordinary humans too would cross on sudden impulses -

He just happened to possess these two traits at once.

He had not the charisma to lead an evil force; he was but a creature that couldn't seem to have enough of what intrigued him.

Kishitani Shinra had made the following comment about Izaya when they were both in high school:

[I'll tell you what you are. You're kind of on the bad side, but you are not completely evil. Yet there's not a single ounce of goodness in you, either. Hmm, how should I put it…if I were to try to sum you up in one sentence - it would be something like "You make me want to throw up." - And that was a compliment, you know.]

Izaya had merely laughed when his almost-only friend said this. But in fact, he too thought it was right on the spot.

from here