"It is most difficult to believe that something so beautiful could be dangerous."
— Teal'c
The team is exposed to an addictive alien light that causes extreme withdrawal symptoms including depression, suicidal behavior, coma and eventually death in anyone who leaves its immediate proximity. O'Neill begins to suspect that the planet's only inhabitant, a teenager named Loran, knows more about how the light works than he's letting on.
"The Light" provides examples of the following tropes:
- Armor-Piercing Question:Loran: I'm sorry you can't leave.Daniel: Are you?
- The Bet: Carter is not amused to discover that O'Neill and Daniel have apparently been betting on whether or not she could be persuaded to visit the planet.
- Captain Obvious: When O'Neill, Carter and Teal'c find a room filled with hypnotic glowing light:Teal'c: I believe this is the room of light of which Daniel Jackson has spoken.O'Neill: ...Really?
- Continuity Nod: When Loran shows Teal'c a toy phaser that lights up, Teal'c laments the Earth custom of making weapons that serve no effective combat purpose, recalling both the light-up laser gun he found in Martin Lloyd's house and the super soakers introduced to him when he played with Ally.
- Driven to Suicide: Lt. Barber kills himself in The Teaser by running into the unstable vortex of an opening wormhole, Daniel almost jumps from his balcony and Loran reveals that his parents walked out to sea and allowed themselves to drown. The implication is that anybody going through withdrawal from the light will eventually attempt suicide if their condition is left unchecked.
- Fantastic Drug: The light, or rather, the undetectable energy being given off at the same time. Daniel describes it as a Goa'uld opium den. The undetectable energy being given off generates an altered physiological state that works like a drug high without the chemicals. Anyone without a Goa'uld symbiote (Goa'uld or Jaffa) to correct the chemical imbalances will die if they leave the area unless the energy is slowly "turned down" in increments first to avoid going cold turkey. Goa'uld and Jaffa can leave at will and their symbiotes will automatically correct it, while the human slaves are stuck there while their masters are "high", unable to leave. The light is just something pretty to look at, that takes advantage of the altered physiological state. It's basically the technological equivalent of "whoa dude, look at the pretty colors, I can taste them".
- Get A Hold Of Yourself Man: O'Neill shakes Carter to snap her out of her stupor when she's transfixed by the light. He later does it again when she goes into withdrawal and starts trying to pick a fight with him.
- I Just Want to Have Friends: Loran. Somewhat understandable given that he's been living alone in an empty palace for an unspecified amount of time.
- The Immune:
- Although Teal'c is susceptible to the addictive effects of the light, he is able to leave its vicinity without succumbing to withdrawal as his symbiote will automatically correct the physiological imbalances. This makes sense, because the Goa'uld designed the place to give themselves a drug high without the chemicals. They wouldn't create something that would kill them. But it would kill any of their human slaves that tried to leave the area while their masters were "high", so it also served as a way to keep the slaves under control during that time.
- Loran is unaffected by the narcotic effect of the device as it was designed to affect an adult's physiology, not a child or teenager's, though he still has the physical dependence on the device's energy.
- It's All My Fault: Loran blames himself for the deaths of his parents after he grew frustrated by their obsession with the light and turned it off, not realizing that it would cause them to kill themselves.
- Missing Time: Anyone looking at the light for too long begins to lose all track of time.
- No Longer with Us: Played for Drama; despite knowing full well that his parents are dead, Loran keeps repeating that they "not here" and talking about them like they're simply on another part of the planet and due to return any minute. After they find the bodies, O'Neill finally snaps at him that "they're not coming back," prompting him to admit the truth.
- Over-the-Shoulder Carry: O'Neill carries Daniel through the stargate this way to get him back within range of the light when his withdrawal causes his heart to stop.
- Really 700 Years Old: Teal'c tells Loran that he is 101 years old, though birthdays are not celebrated on Chulak.
- Red Shirt: All the members of SG-5 die from withdrawal.
- Sole Survivor: Loran is implied to be the only person on his entire planet following the deaths of his parents, or at least the only one in the immediate vicinity of the stargate.
- Talking Down the Suicidal: O'Neill does this when he goes to Daniel's apartment after he fails to show up for work and finds him standing on the wrong side of the balcony, preparing to jump.
- Tantrum Throwing: Daniel slams a book on his desk, is angry that he can't get an alien device to work and then goes to Hammond's office and shouts that he must return to the planet immediately. O'Neill knocks over a tray of medical equipment in the infirmary as his worry over Daniel's condition is amplified by the effects of his own withdrawal.
- They Killed Kenny Again: Daniel briefly dies as a result of his withdrawal, only to recover when O'Neill returns him to the planet.
- Took a Level in Jerkass: One of the first signs that a person is in withdrawal from the light; Daniel starts yelling at Hammond and acting like an entitled brat when he doesn't get his own way, O'Neill snaps at Fraiser and calls her a "dumbass", and Carter starts acting insubordinate towards O'Neill.
