"Death can only offer a temporary escape. I can revive you again and again — a thousand times if need be. Only once you have told me everything I ask will you be allowed to die one... last... time."
— Ba'al
O'Neill is taken prisoner by Ba'al and repeatedly tortured for information pertaining to the Tok'ra symbiote he was implanted with; information he claims to have no memory of. In between torture sessions, he is visited by Daniel, who offers to help him ascend but is forbidden from intervening in any other way.
"Abyss" provides examples of the following tropes:
- All-Powerful Bystander: Daniel theoretically has the ability to obliterate Ba'al's forces and bust O'Neill out, but his hands are tied due to the ascended non-interference clause.
- Badass in Distress: O'Neill continues to snark at Ba'al throughout his ordeal — though he outright admits that he's about to crack towards the end of the episode — and he manages to escape on his own once Yu's attack gives him the opportunity.Ba'al: You will suffer for this impudence!
O'Neill: Don't know the meaning of the word! [Beat] Seriously. Impudence. What's that mean? - Batman Gambit: The rest of the team pull off one of these by sending Lord Yu the plans for Ba'al's outpost, correctly predicting that he will attack and O'Neill will take the opportunity to fight his way out.
- Bearer of Bad News: The Tok'ra Chancellor Thoran uses the exact words when he arrives to inform Hammond of O'Neill's disappearance.
- The Bus Came Back: Ba'al returns for his first appearance since "Summit" and "Last Stand" the previous Season. This return formally cements him as a recurring character — a run which will last through the end of the series and into the Direct-To-Video films.
- Cold-Blooded Torture: Not content with the usual tactics employed by the Goa'uld, Ba'al gets truly creative in his torture, using knives and acid to bring O'Neill to the brink of death and revive him in the sarcophagus over and over again.
- Continuity Nod:
- Thoran mentions that the Tok'ra are still scattered following the attack on Revanna.
- O'Neill asks if Daniel can summon lightning, a reference to Oma Desala's attack on Apophis's Jaffa in "Maternal Instinct".
- Daniel is concerned that O'Neill will begin to lose who he is if he keeps being put into the sarcophagus.
- The notion of System Lords having a highly trusted human slave called a Lotar was established in the episode Summit.
- Death Is Cheap: Gets deconstructed and played for horror, with Ba'al killing O'Neill over and over again in horrifically painful ways only to revive him and begin again, with the result that the idea of a permanent death to escape the torture starts looking like a reward.
- Enemy Mine: A distant example; The SGC tips off Lord Yu about Ba'als secret base and he attacks. Naturally he has no interest in helping O'Neill, he's just striking at a rival, but it does give O'Neill the chance he needed to escape.
- Energy Being: Although Daniel appears in human form, he still lacks a physical body and is completely intangible, which O'Neill demonstrates by throwing a shoe through him.Daniel: I'm... I'm energy now.O'Neill: How's that working out for you?Daniel: Good, actually.
- Fantastic Racism: Thoran accuses Hammond and the rest of the team of this regarding their attitude towards the Tok'ra.
- Faux Affably Evil: Ba'al acts like this most of the time he's torturing O'Neill, pretending to sympathize with his predicament and even neutralizing the pain when O'Neill gives him some useful information.
- Friendship Moment: Most of the scenes between O'Neill and Daniel.
- Gravity Screw: The gravity inside O'Neill's cell is changed every time he gets put inside, so that what he enters as a long hallway with a dead end and no door becomes a deep pit with sheer walls, with the far wall becoming the floor. While going through the plans for Ba'al's fortress, Jonas explicitly states that one of its intended purposes is to conduct research into gravity technology.
- I Cannot Self-Terminate: After a few rounds of torture, O'Neill asks Daniel to kill him in such a way that Ba'al will not be able to bring him back. Daniel refuses to even entertain the idea.O'Neill: Any minute, they're gonna come. Ba'al's gonna kill me again. You can make it the last time.Daniel: Don't ask me to do that.O'Neill: You can put an end to it.Daniel: I won't do it.
- In the Back: O'Neill, or rather Kanan, is shot in the back by one of Ba'al's Jaffa at the beginning of the episode.
- Maybe Magic, Maybe Mundane: It's left ambiguous whether Carter and Teal'c's epiphanies regarding how they can help O'Neill were due to Daniel covertly influencing them or not. On the one hand, it's not exactly uncommon for SG-1 to pull solutions out of thin air, but on the other hand Daniel did disappear for a while around the same time and say that there was "something he had to do".
- No-Holds-Barred Beatdown: After escaping from his cell, a very frustrated O'Neill comes across one of the guards and absolutely pummels him, continuing to punch him in the face even after he's down and out.
- No One Gets Left Behind: Hammond tells Thoran that this is where the SGC is different to the Tok'ra; they don't leave their people behind. This actually becomes important when Carter speculates that Kanan was only motivated to return for the slave Shalln after blending with O'Neill, since he would have taken on all of O'Neill's ideologies.
- Obfuscating Stupidity: Daniel calls O'Neill out on his tendency to downplay his intelligence when he insists that he's not cut out for ascension:Daniel: Oh, come on, Jack! You think the Asgard named a ship after you because they thought it was a cool name? Now's not the time to play dumb, you're a lot smarter than that.
- Running Gag:
- When O'Neill gives his name to Ba'al, he clarifies that it's two 'L's.
- Daniel quotes Oma's "if you immediately know that the candlelight is fire, then the meal was cooked a long time ago" koan.
- Star-Crossed Lovers: O'Neill claims that Kanan had legitimately fallen in love with Ba'al's slave Shallan, which is why he undertook a secret mission to free her.
- Torture Chamber Episode: The entire episode revolves around O'Neill being subjected to brutal torture, mostly for information that he doesn't remember.
- Torture Technician: Ba'al definitely has a certain skill in this area that none of the other Goa'uld really possess, coming close to breaking O'Neill by the end of the episode.
- You Are Better Than You Think You Are: Daniel wants to help Jack ascend so he can escape his cell. Jack very firmly denies being enlightened enough to do this.
- You Are Not Alone: The entire point of Daniel keeping O'Neill company in his cell in between torture sessions, since he can't actually do anything to stop it.
- You Would Do the Same for Me: O'Neill inverts this by telling Daniel that if their positions were reversed and Daniel was the one being repeatedly tortured to death, O'Neill would do everything in his power to break him out — and if that wasn't an option, he'd at least do him the favor of a Mercy Kill to put him out his misery.O'Neill: I'd do it for you, and you know it.
