Because no one can read/watch Durarara! without some Shizuo love.
The title comes from Job 5:7, which says "Yet man is born unto trouble, as the sparks fly upward." Fits Shizuo pretty well, yeah? And the "sparks" can also refer to something which I mention at the end of this…hehe~
If you've never read the light novels, you should do so. They give a lot more insight into Shizuo's character that isn't covered as much in-depth in the anime. You can find most of them on anni-fiesta's livejournal. (Sorry, I can't get the links to work here.) The snippets I particularly drew from for this are "Interviewing Shizuo" and "Shizuo talks about his past with Celty." Go read them RIGHT NAOW!
Now please, enjoy.
As Sparks Fly Upward
He is nine years old the first time his inhuman strength shows itself and he nearly kills his little brother over a petty argument he can't even remember now. Fortunately, his childish body cannot take the weight of the refrigerator and he crumples beneath the strain of it. As his brother runs from the room, screaming for an ambulance, his anger ebbs away as quickly as it came, and he is left grateful for the pain of his broken body, even as he writhes on the floor.
At ten years old, Shizuo comes to the startling realization that his luck will not always work in his favor as it did the first time with Kasuka. His body will not always break down and save him from the catastrophic results of his anger before it's too late. He realizes this as he stands panting amid the remains of a bakery shop, and even with one arm already in a sling, he has caused this much destruction and hurt someone he meant to protect.
A seed is then planted in his brain, the seed of an idea that he barely even notices at the time, but slowly starts to recognize over the years: perhaps no one will ever be able to get close to him again because of this monstrous strength. Perhaps he'll be alone for the rest of his life.
Shinra has many hypotheses about Shizuo's strength. Shinra always has many things to say, and is particularly fond of saying them when Shizuo is trapped in a hospital bed, unable to escape, and only able to shut up the aspiring doctor if he's foolish enough to stray within arm's reach. But Shinra learned quickly after the first few times.
He is convinced that Shizuo's inhuman strength is directly related to the degree of his anger, in the same way that the human brain would normally relate the strength of adrenaline power to the degree of emergency. If that's the case, Shizuo inwardly wonders if his uncontrollable rage is not also to blame on his brain. After all, if the limiter that would normally control his "adrenaline power" is apparently broken, couldn't it also be that the area of his brain that would normally put a limit on his anger might also be broken in the same way? In that case, he can hardly be blamed for losing his temper so often if it's a problem in his brain.
However, Shizuo knows that he is simply making excuses for himself. It's his own fault and no one else's that he can't control his rage, and he's long given up even trying to. But as long as his body keeps destroying itself at the same time that he destroys everything around him, it'll be all right. He doesn't give his body a chance to heal before he's destroying it again, and he thinks that maybe if he destroys it enough times, one day he'll finally just cease to be.
His hope begins to fade with time, however, as his body just becomes stronger and more resilient with every broken bone, dislocated joint, and torn muscle that he forces on it. By the time he's sixteen, he has stopped breaking bones. Even the previous year, when that conniving flea Izaya tricked him into getting hit by a delivery truck the first day they met, he merely lay on the pavement, winded, for a few minutes before he was able to pick himself up and storm over to Shinra's.
Shizuo begins to wonder if there's anything that can kill him. He's survived being beaten, stabbed, hit by a truck, and sustaining more musculoskeletal damage than any normal person would ever see in a lifetime. Most of the nurses and many of the doctors at the hospital are on a familiar first name basis with him from his frequent stays there. Is this how he will live the rest of his life? Cursed with an uncontrollable power, at constant risk of losing himself to his rage and harming someone he cares about? Seven years after the first incident, he can now freely lift the family refrigerator with no risk of damage to his body. What would happen next time Kasuka does something to upset his extremely volatile brother? There would be no luck of dislocations and torn muscles to save Shizuo a second time from a moment of anger he would regret the rest of his life.
Kasuka…Kasuka is the greatest source of Shizuo's internal guilt. Even though Shizuo has never physically hurt him (yet—it's only a matter of time, he reminds himself), he knows that he has hurt his little brother in other ways that he will never recover from. He didn't notice it happening at the time (was usually too involved being lost in his rage and then recovering from his self-induced injuries), but he remembers when he first noticed his little brother doesn't show emotion like a normal person does. Kasuka would never say anything to him about it, but Shizuo doesn't need to ask. He knows without a doubt that he is responsible for the way his little brother has sealed away all his own emotions. In order to balance out Shizuo's overwhelming anger and raging, Kasuka has taken it upon himself to become a completely blank slate of emotionlessness.
Years later, when Hanejima Yuuhei is a successful actor with millions of screaming fans nationwide, Shizuo suspects that the reason Kasuka began acting at all was so that he'd have the freedom to express all the human emotions that he normally doesn't allow himself. And Shizuo writhes in his guilt. All he has ever wanted is to be able to protect Kasuka, to be a good older brother to him. But all the strength in the world is not enough to protect him from Shizuo. He isn't stupid. He knows Kasuka would have been better off without him.
Perhaps it's not too late.
Shizuo half-believes that maybe he is invincible—but it's not arrogance, more of a dull dread that just keeps building over the years. What if he just keeps going on and on, his body getting stronger and stronger and stronger? Meanwhile everyone around him will be hurt or killed or too scared to get close to him. Will he keep going on forever? Will his body one day consume itself after there is nothing else left to destroy? He doesn't really want to wait to find out.
The first way he tries is hanging. That's a pretty typical way to go, right? Afterwards, he berates himself for his stupidity while he angrily tears down the remains of the broken noose. Of course that couldn't kill him. He's already broken his neck three different times in the past and didn't die from it. Now that his bones no longer break, what did he really expect to happen?
The next method he tries is pills. No matter how tough his bones and muscles have become, his insides should still be vulnerable, right? But his body rejects the overdose of sleeping pills and he is left merely drowsy the rest of the day.
Almost at a loss, Shizuo next sneaks a kitchen knife to the bathroom and slits his wrists over the sink. He is left in despair as he watches the deep wounds begin to clot before he can even begin to feel the effects of the severe blood loss.
He doesn't think jumping from a tall building would work, probably just give him a headache. He doubts even a gun would do the trick, and anyway, where would he even get a gun? He supposes maybe drowning would work, if he can just make himself stay underwater long enough, because even his indomitable body needs air to survive, right? However, Shizuo can't bring himself to bother anymore. He figures something else would just get in his way, and by now he's given up trying to do away with himself when the universe is clearly against it.
Shizuo is seventeen when a rather unexpected occurrence makes him think he can die, after all, and at the hands of his nemesis, no less. He was chasing Izaya after school (had been chasing him since around lunch time, actually) and the two were approaching the outskirts of the city, Izaya leading the way over one of the many pedestrian overpasses that crossed the train tracks, Shizuo racing close behind him. A cacophony of train horns blared beneath them as Izaya suddenly stopped and spun around with no warning, kicking his foot straight into Shizuo's chest and sending him flying over the railing and into the path of the trains directly beneath.
Shizuo could only watch in shock as Izaya's smirking face grew further away and the thundering of a train horn grew deafening in his ears. The last thought he had before darkness overwhelmed him was a dichotomy between relief that he's finally met his end, and wonder that the flea's scrawny legs could be so powerful. Then again, he supposed, fleas did use their legs to hop around annoyingly all day, so he shouldn't really be that surprised.
When he wakes, he immediately recognizes his surroundings not as the afterlife, but the too-familiar walls of the hospital. Kasuka is sleeping beside the bed, sitting in a plastic chair with his head resting on his folded arms beside Shizuo's hand. Looking back years later, Shizuo considers those five days he was in a coma to be among the best of his life.
His family had been convinced that this time he was really done for. Once Shizuo realizes that he's not, that he's going to survive and be just fine after being hit by a train, of all things, he can feel the tendrils of despair that had been slowly creeping into his heart over the years now rise up and choke the last shred of hope out of him. When Kasuka wakes up to find his brother staring at the ceiling with tears streaming silently down his face, he immediately leaves to fetch a nurse or someone who can help with the pain. Shizuo watches his brother's back as he walks out of the room and the tears only fall harder.
He is eighteen and it is not long before graduation when Shinra excitedly regales him with the tale of an autopsy he got to assist in the previous night. The man was 46 years old and a leading member of a local yakuza gang. He had died of lung cancer, but the boss had ordered an autopsy anyway, to be sure there were no signs of foul play—no doubt just looking for an excuse to start a war with a rival gang.
The man had been a long-time chain smoker, Shinra informs him, and it was undoubtedly the cancer that killed him. The young doctor-to-be takes great delight in describing to Shizuo in vivid detail the exact texture of the shriveled lungs after he removed them, the sick greyish black color, the way parts of them almost crumbled in his hands. Other than the damage to his lungs, though, the man had been the picture of health.
That same day after school, Shizuo buys his first pack of cigarettes and smokes them all that afternoon, one after another.