(this page is just a placeholder which needs Wiki Magic where we might later import some of the beautiful essays written on Headscratchers,YMMV, and the main page which is getting rather verbose with character analysis.)
He is such a sociopathic narcissist he is incapable of loving anyone but himself.
Ship Tease - Light and Misa, L and Misa, Light and L, Light and Takada
It's not that uncommon to find other characters displaying feelings for Light, but both the manga and the anime give subtle hints about Light having feelings for them, leaving the audience to wonder what's really going on here...
Everyone who has had a conversation with Misa knows that she adores Light. But — and in the manga only — there are some very subtle hints that Light might have had some feelings, or the possibility of some feelings, for her. Specifically, when they first meet and she's explaining the shinigami eyesight to him, he leans in very close to her, catches her eye, compliments her with "You're pretty good at explaining," — and then realizes what he's doing and abruptly draws back, thinking to himself, "I can't develop feelings. That's how most idiots screw up." He even has a bit of a sweatdrop; Misa, of course, is blushing. This scene did not find its way into the anime and the official guidebook states that Light hates Misa as much as he hates L ... although, truth be told, you've got to wonderabout that, too.
It's definitely debatable, but a few sequences in the anime seem to give (subtle and admittedly ambiguous) clues about Light's feelings for both L and Misa. In episode 26, after Light manipulates Rem into killing L, Light hallucinates L sitting next to him (mouthing something that's been speculated to be "Raito-kun?") and gazes numbly at the computer. The scene then cuts to Light and Misa on a date, Light still with that numb look. Completely out of the blue, he asks Misa to move in with him — he doesn't sweet-talk her, he just blurts it out. She cheers, but Ryuk, who usually has something snide to say, just looks away.
There's also a scene in the anime (admittedly where Light is in his amnesiac Nice Guy mode) where Misa, tired after a long day, turns in for the night asking Light if he'd like to sleep with her, which he gets noticeably flustered about. She then says she's joking and knows that he's "saving her" for after the Kira case. Light becomes even more noticeably and vocally flustered after L teases him about being shy.
In one of the bonus strips, admittedly oriented towards a more humorous and light look at the series, in the thirteenth volume, Misa tells Light that she wants to give up the Death Note. Light's reaction is to grab her shoulders and protest that they're going to create a new world together, and that he needs her.
L and Misa
In the Live Action movie, there are definitely hints of a ship tease between Misa and L when they first meet. And then L proceeds to lock Misa up and restrain her in a unnecessarily perverted-looking way.
They are chained together for months. They stare at each other... a lot. L gives Light a symbolic foot massage... while they are both dripping wet and romantic music plays in the background.
L is Light's Not Love Interest. L evokes feelings in Light that he feels for no one else. L is the most important person in Light's life even after he is dead. And in the anime L is the only person on Light's mind when he's dying.
However even if Light has feelings for L he would never act on them because his crusade comes before anything else. If Light wants to be God of the New World L has to die. Simple as that. Though it's telling that has to remind himself of this after L invokes The Power of Love and The Power of Friendship against Kira with his lie of "I feel as if you are the first friend I've ever had." For a moment it almost seems to sway Light-he gets a very shocked look on his face and in the anime the same music that played when Gelus died for love starts playing. (The only way to kill a Shinigami is to get it to fall in love with a human and as Ryuk joked earlier Light is "already a worthy Shinigami.") L doesn't have many other cards to play other than emotional manipulation. He probably hopes to catch Light off-guard-if he gets Light riled up enough he might make a mistake so that L can catch him and have him executed. L certainly succeeds in getting under Light's skin as Light continues to obsess about L as he walks home up until he's glomped by Misa, sounding very much like a Tsundere all the way as he curses L's name (or rather his alias). Ryuk mocks this development in a very suggestive tone:
Light: That DAMN Ryuuzaki!
Ryuk: Friend. *snicker* He's your friend. But that's a good thing, isn't it, Light?
Yeah, that DAMN Ryuuzaki, saying he's my friend. It's not like I like you or anything!
Later Light has to remind himself that L is NOT his friend. "Light Yagami and "Hideki Ryuuga" appear to be friends but L is Kira's enemy."
Also during the Yotsuba arc when Light has lost his Kira memories and the knowledge that L is his enemy, you'd still think he'd be a bit upset with L for confining him for 50 days and making his father carry out a mock execution, yet when L ends their confinementLight seems not to hold any grudge against L for locking him up and indeed seems quite thrilled about the idea of being with L 24/7.
It is interesting to note when L is dying Light gets teary-eyed about it for about two seconds before displaying that memetic rape face.
Light and Takada
Here's an in depth essay on why some fans find Misa's character to be disagreeable, as well as a Light/Takada ship manifesto. It also points out some major differences between the manga and anime.
Light is also often labled a sociopath by fandom, however L and Near fit the criteria better than Light does! See more at this fan essay: "Light is not a Sociopath"
Post-Death Note Light is absolutely a sociopath. The linked essay provides a list of seven symptoms of Antisocial Personality Disorder. Light fits the four most important ones: 1. Failure to conform to social norms with respect to lawful behaviors as indicated by repeatedly performing acts that are grounds for arrest; 2. Deceitfulness, as indicated by repeatedly lying, use of aliases, or conning others for personal profit or pleasure; 5. Reckless disregard for safety of self or others; 7. Lack of remorse, as indicated by being indifferent to or rationalizing having hurt, mistreated, or stolen from another.
Furthermore, there are two problems with the essay: A) The choice to use the question of an APD (a condition associated with criminality) diagnosis to examine whether or not Light was a sociopath (which is a term not in psychiatric use) ignores the fact that most sociopaths are not criminals; they simply lack empathy and remorse. Most of them lead normal lives and can have quite successful careers. Light's lack of criminal or antisocial behavior prior to acquiring the Death Note is clinically insignificant. B) It ignores the fact that Light becomes incredibly sadistic as the story moves along (with the beginnings of it showing up relatively early on). Light has plenty of other problems regardless, such as Black and White Insanity, Narcissism, and Lack of Empathy.
Among the causes of narcissism are listed: being praised for perceived exceptional looks or abilities by adults, excessive admiration that is never balanced with realistic feedback, and unpredictable or unreliable caregiving from parents. Although these are never explored in depth, Light has definitely experienced praise for being exceptional: a great athlete, a great student, a great son, intelligent, handsome, and so forth. And even Soichiro himself admitted that his work as a policeman kept him away at odd hours from Light and Sayu.
Pathological narcissism is considered to result from a person's unconscious belief that they are flawed in a way that makes them fundamentally unacceptable to others. Light does indeed have a flaw (he is a serial killer out to rule the world) that would make him fundamentally unacceptable to others, and he has to live with this, both consciously and unconsciously, for years. His classification of those trying to expose and condemn him as evil ("They're the evil ones!") can be seen as a defensive mechanism, protecting his view of himself ("I am righteous! I protect the innocent!").
People matching the diagnostic criteria for narcissistic personality disorder use black and white thinking, called splitting, as a central defense mechanism; they separate mental concepts into good versus evil, say, as an attempt to stabilize the sense of self in order to preserve self-esteem. Throughout the series Light certainly does show clear indications of perceiving himself as purely upright or admirable and others who do not conform to his will or values as purely wicked or contemptible.
Light has a grandiose sense of self-importance, viewing himself as special and unique (chosen to rid the world of evil), as someone who will become the God of the New World. Going on with this, he frequently indulges in fantasies of unlimited success and power (Godhood).
Light is extremely interpersonally exploitative: he takes advantage of people to achieve his own ends, and feels entitled to their admiration and compliance. Look at his relationships with Misa Amane, Kiyomi Takada, and Teru Mikami in particular: he enlists them to help him avoid capture and achieve his goals and leaves them when convenient for himself. He is floored with Mikami does not obey his instructions to the letter, and he actually calls out to Takada and Misa for help at the end, even though Takada is dead and he has effectively abandoned Misa.
Light grows to utterly lack empathy by the end of the series. In the earlier episodes, he indicates sympathy for his father and care and support for his sister, and is noticeably affected when L calls him his friend (although he gets rid of it fairly quickly). As his delusions grow stronger, however, Light completely disassociates himself as Kira from those around him. If constantly making use of Misa's and Takada's affection and trust for his own ends with nary a thought wasn't enough for you, just look at how he essentially abandons Misa and finishes off Takada. Technically Mikami killed Takada, but Light still fully intended to make her burn herself to death after begging him for help, and didn't feel a thing.
Light is unable to see any flaw in himself, which is the main thing that separates him from L and what leaves him devoid of any empathy. It is probably the fact that L is Not So Different that makes Light consider him a Worthy Opponent. Light usually sees positive traits in L ("L will probably figure out this", "L is too smart to fall for that") because those are positive traits he sees in himself. On the other hand, L is aware of his own flaws; he immediately assumes Kira is childish and hates losing because L himself is like that, and admits that even if Misa had carried on with her threat of the police to make them expose L, he wouldn't have appeared on TV because he isn't that noble. This is reflected upon each's plans for the world, Light believes in a perfect world filled exclusively with good, respectful, working people, where everything and everyone is perfect just like him. L, and later Near, see the world as flawed and seem pretty ok with it, since they're pretty ok with their own flaws. Ironically, it's the awareness of their own flaws that keeps them in the gray of the Black and Gray Morality while Light's vision of himself as perfect is what leads him to become a monster.
Despite being a dark crime thriller with a megalomaniacal mass-murderer for a protagonist, when you get down to it it contains all the basic elements of a typical shonen series, albeit in forms twisted nearly beyond recognition: a young, justice-loving Chaste Hero (a narcissistic Knight Templar with delusions of godhood) who discovers magical powers (a notebook that can be used to instantly murder anybody) and gains a Spirit Buddy (an amoral embodiment of death), makes a Worthy Opponent rival (a detective trying to apprehend him for his crimes) who knows martial arts (Capoeira) and picks up a persistent Genki Girl love interest (a vapid pop idol who's fanatically obsessed with him and, despite barely knowing him, is instantly willing to kill for, die for and marry him). If the satire was intended on the part of Tsugumi Ohba, he/she sure hasn't let on.
Much of the story is spent waffling on about "justice" and "righteousness", and all of the characters seem to believe that, because Right Makes Might, their ideals will cause them to be victorious. They all, particularly Light and L, stick very closely to this mindset for most of the story. Then we get this statement from Light:
Light: If we catch Kira, he is evil. If he succeeds, he is justice.
That is, justice will prevail - but not because it is good or right. Justice will always prevail, but only because whoever wins will claim it. There is no true justice; it's not Right Makes Might, but Might Makes Right. Then, at the end of it all, nobody prevails; they're almost all dead, and nothing changes. Nobody was saved by this ordeal. That's because the entire concept of justice is fundamentally flawed, particularly in this series' Grey and Grey Morality. There is no 'good' or 'evil; everything simply is. That's why there's no heaven or hell, and that's why neither Light or L made it to the end alive. They were fighting against an evil that never existed to begin with. They were doomed from the start, because their entire frames of thinking were wrong.
Ryuk: If they put you in prison who knows when you'll die?
Ryuk would, being able to see his lifespan, but Light wouldn't. In the Japanese justice system they don't announce the day of execution—and it would be death by hanging, not lethal injection. As a death row inmate he could've had to wait up to thirty years in solitary confinement not knowing if today would be his last. Many inmates are known to have mental breakdowns due to the stress of waiting and Light is not the picture of mental stability to begin with. That of course is even assuming that he'll even get to stand trial to be sentenced to death—in the manga it's strongly implied that Near wanted to keep him as his own personal toy.
Want to write the next Death Note? Try So You Want To Write A Magnificent Bastard
Back to Death Note.