Vive la résistance!
Victor Laszlo is a Czech who's been fighting with the resistance. He's married to the beautiful Ilsa. He's come with her to Casablanca hoping to snag a couple of exit visas so he can go to America and continue his work.
In just about any other movie, this guy would be our hero. He's handsome, kind, charming, humble, and he's practically fighting the Gestapo single-handed. He's got the scars on his face to prove it. Show him helping a couple of elderly women across the street and he's pretty much the perfect gentleman. He's absolutely devoted to the cause of freedom:
RICK: Don't you sometimes wonder if it's worth all this? I mean, what you're fighting for.
LASZLO: You might as well question why we breathe. If you stop breathing, we'll die. If we stop fighting our enemies, the world will die.
But we're not always rooting for victory for Victor. To outmaneuver the Germans, sure. But when it comes to the love triangle, he's an unwelcome hypotenuse.
So why aren't we Team Laszlo? Why haven't we all boarded the express train to Victorville?
Part of the reason is that Rick is clearly our protagonist. Everything is centered around him. He gets the most screen time, we get the best look at his motivations; even his faults we learn to accept, and even find endearing. So when our hero (Rick) wants something or someone (Ilsa), but someone else (Victor) is standing in his way…well, whether he's the woman's husband or not, we sorta want him out of the picture. Which totally isn't fair.
Even after Victor begins to suspect something, (why is Rick refusing to sell him the visas?) he's understanding about it. He tells Ilsa he knows she must have been lonely and frightened in Paris after he went missing, and sort of forgives her without really saying anything about her and Rick.
It gets better. In a last ditch effort to get those visas, he even offers to sacrifice himself so that Ilsa can get out. He tells Rick:
LASZLO: I know a good deal more about you than you suspect. I know, for instance, that you are in love with a woman. It is perhaps a strange circumstance that we both should be in love with the same woman. The first evening I came into this cafe, I knew there was something between you and Ilsa. Since no one is to blame, I, I demand no explanation. I ask only one thing. You won't give me the letters of transit. All right. But I want my wife to be safe. I ask you as a favor to use the letters to take her away from Casablanca.
RICK: You love her that much?
LASZLO: Apparently, you think of me only as a leader of a Cause. Well, I am also a human being. Yes, I love her that much.
In most films, once the hero is clearly delineated, the guy-in-the-way will be made out to be some sort of villain, or at least an undesirable, so that it's easier for us to draw the line in our brains. But that's what makes Casablanca so beautifully complex—it doesn't provide any simple answers to our questions, and it challenges us to defend our instincts. Of course, once Rick loses the girl and she flies off with Victor instead, the fact that he's such a great guy makes the somewhat unhappy ending a bit more palatable. But in the meantime, his very existence is kind of a pain in the butt for the moviegoer who wants things to be all wrapped up simple-like.
When it comes down to it though, Casablanca isn't just a love story. It's about standing up to tyranny, and fighting for what's right, and Laszlo is all over that stuff. He's not afraid of Major Strasser and he's not afraid to die for the cause. He isn't struggling with all that inner turmoil that Rick is, which makes him perhaps a less complex character, but certainly not a less noble or likable one. Even Rick, his rival in love, admires him:
RICK: We all try. You succeed.
We're sure Victor went on to do some great things in America with Ilsa there to support him. Maybe he's the one who convinced FDR to enter the war. Well, that and Pearl Harbor.