Folks, this dude's name comes from the Russian word for "mosquito."
That should tell you all you need to know.
We mean, if you're looking for an insect—or an antagonist—in this book, the Moscow lawyer Komarovsky is your man. This old lawyer is pretty much a great example of everything Pasternak finds wrong with the world. For starters, we know that this guy isn't going to be a role model the moment he starts ogling his girlfriend's daughter: "[Lara's] shock of hair, scattered in disorder over the pillow, stung Komarovsky's eyes with the smoke of its beauty and penetrated his soul" (2.13.5). Pasternak is nice enough to describe Komarovsky's lust in poetic terms, but that doesn't make him any better of a man.
If that weren't enough, Komarovsky is pretty much the opposite of Yuri Zhivago. When the Russian Revolution breaks out, Komarovsky makes sure to have powerful friends on both sides of the conflict. He rises up the social ladder and constantly profits from not taking sides... and from always slithering his way into people's good books.
Okay, okay: for all of that, even Komarovsky has a conscience. When he's having his fling with the young Lara, for example, he starts to despise himself for being a lusty old man who hangs out with other lusty old men. As the narrator says, "He imagined Kuznetsky, Satanidi's jokes [about Lara], the stream of acquaintances he was going to meet. No, it was beyond his strength! How repugnant it had all become!" (2.13.6).
Normally, Komarovsky would love to walk around town talking about his sexual conquests. But with Lara, he knows he's gone too far, and out of guilt, he spends the rest of the book doing whatever he can to protect her. Even then, there's a hint that he might be trying to one-up Zhivago in Lara's eyes, but it does seem pretty clear that he legitimately wants to help them.
At the end of the book, Komarovsky tries to do well by Lara one last time by getting her away from the Russian police. While he's doing this, he tries to explain his position to Zhivago, Lara's lover, by saying that there "exists a certain Communist style. Few people measure up to it. But no one so clearly violates that way of living and thinking as you do, Yuri Andreevich" (14.1.19).
In other words, he's telling Zhivago to give up his individuality and try to fit in like everyone else. After all, this strategy has benefitted Komarovsky a lot. Fortunately, Zhivago actually has principles that he lives by, and at the end of the day, Komarovsky basically doesn't.