After the events of H'el on Earth, H'El has been sent back in time to the period of Krypton's explosion. Using his knowledge of the future, H'El hopes to save Krypton, but his actions begin to cause great damage to the universe. Superman and his allies travel to the past in order to stop him.
Krypton Returns contains examples of:
- Action Mom: Lara. She even attacks Superman, believing him an intruder when he enters the House of El. Superman, who is seeing his mother for the first time, is astonished. She also trained a pre-Supergirl Kara in at least some combat techniques.
- All-Powerful Bystander: The Oracle, the cosmic entity that sends the Superman family back in time to stop H'El, is extremely powerful but his species have an Alien Non-Interference Clause. Because of the threat H'El poses to all reality, the Oracle breaks this rule.
- Always Chaotic Evil: All clones during the Great War are portrayed like this.
- And I Must Scream: Superman traps a badly wounded H'El in an infinite time loop within Krypton's core that will preserve him within a few endlessly-repeating seconds of time for all eternity. This is the alternative he chose over killing him, declaring that doing so would be wrong.
- Anti-Hero: Faora. After H'El killed General Zod, she became the Oracle's new herald.
- Apocalypse How: Three.
- Class 1: H'El has caused one on Krypton, turning it from what Kryptonians would consider perfect to a degree into a Villain World that even Faora is appalled by.
- Class X: What the Superman Family has to make sure still happens: the destruction of Krypton and escape of the select few inhabitants needed later.
- Class Z: If H'El succeeds, the ensuing Time Crash will cause one of these that stretches not just to the edges of Prime Earth or even The Multiverse, but the Omniverse, which includes, according to the wiki, other enterprises such as the Marvel Universe.
- Artificial Human: H'El is revealed to be this in Superman #23.3. He was created from a collection of genetic material gathered all over Krypton's history by Jor-El in an unmanned spaceship to find a planet where the people of Krypton could be safely evacuated to by the time Krypton exploded.
- Asskicking Leads to Leadership: When Supergirl defeats Kon, the clone leader, the clones see her as their leader. They aid her in her fight against H'El.
- Batman Can Breathe in Space: As is common in the New 52, Kryptonians do not have to breathe, as long as their bodies have enough stored sunlight.
- Beat the Curse Out of Him: Supergirl slaps Superboy in order to free him from the Oracle's possession.
- Blood Knight: Supergirl again shows hints of this when handling the clones. Naturally, this means that she fits right in.
- Body Horror: In the finale, an alternate version of Jor-El aids Superman in his fight against H'El. Jor-El hits H'El with a gas that will break him down to his cells. Not wanting to kill him, Superman stops Jor-El mid-process, leaving H'El horribly disfigured and weak.
- Brought Down to Normal: When they are brought to Krypton, the heroes begin losing their powers by being exposed to Krypton's red sun.
- Continuity Nod: This serves as the second appearance of the Eradicator, in this timeline being sent after Superboy to keep him from protecting the past Supergirl.
- Conveniently Empty Building: Taken to the logical extreme. The threat of the Time Crash from H'El's actions is very real, but fortunately for the heroes it is repeatedly stated that the effects are hitting the uninhabited edges of the universe first.
- Crapsaccharine World: What H'El turns Krypton into after he takes over. At first, Krypton looks as the pristine and magnificent world it was before its destruction. Later, it is revealed to have a space station in orbit that attacks intruders and at least one of its moons has a slave camp.
- Demonic Possession: In order to talk to Superman and Supergirl, the Oracle takes possession of Superboy's body. Supergirl slaps Superboy to free him from the possession. Superboy remarks that he could have died if the Oracle spent more time in his body.
- The End of the World as We Know It: If the Superman family does not stop H'El, the temporal distortions he caused will destroy all reality.
- Godzilla Threshold: The state that H'El has put Krypton in, along with the death of Dru-Zod, forces Faora to join up with the Oracle to contact the Superman Family to make sure that Krypton is Doomed by Canon, which she considers a Mercy Kill compared to what has happened to the world.
- Go Mad from the Revelation: H'El doesn't take the revelation of his origin well, to say the least.
- Heroic Sacrifice: Superboy does not make it to the end of the event alive, and thus Jon Lane Kent, the evil future son of Superman, will headline his book and take his spot on the Teen Titans. He notices that the anti-gravity of the city of Argo isn't strong enough to break the city free from Krypton's gravitational pull, so he uses all his power to give the city and Supergirl's rocket the push they need to leave Krypton's atmosphere. The effort expends all of Superboy's power and he expires in the wake of Krypton's destruction, happy with the great deed he's done.
- Which in turn did not last long, as Jon Lane Kent eventually does grow empathy, and decides to essentially commit cosmic suicide to allow Kon-El to live again, whilst essentially erasing the last bit of the Bad Future that he and his "father" Harvest had come from. Superboy eventually goes on a journey of self-reflection, and while Supergirl and the Teen Titans learn he is alive again, in the latter case he's framed for murder and the team enters a schism on believing him innocent or guilty.
- Meanwhile, in the Future…: In Supergirl #25, H'El travels to Superboy's mission's time, while "simultaneously" fighting Supergirl, with the times synching up so that he is hit by multiple Super Family members at the "same time".
- Mythology Gag:
- When Superman begins to lose his powers due to red sunlight exposure, he coughs up a little, just like Man of Steel.
- H'El's origins are a mixture of those of Superman and Zod from Man of Steel. He is formed from countless Kryptonians over the ages, but completely, not just implanted within him as was the case with Kal-El. However, his desire for either having Krypton back or nothing at all harkens to the same film's General Dru-Zod.
- No-Sell: While Kryptonite can pierce H'El's skin, it doesn't sap his strength or poison him. This is because of H'El's origins.
- Ret-Canon: The story arc depicts Faora wearing her Man of Steel armor.
- Sacrificial Planet: In order to show the threat H'El poses, Superman witnesses the destruction of an entire star system.
- Save This Person, Save the World: Supergirl must prevent H'El from causing trouble during the age of the Great War, but first, Superboy must make sure she leaves Krypton in the first place.
- Set Right What Once Went Wrong: The whole premise of the story is to correct the damage H'El did to the timeline.
- Superboy is sent back one week before Krypton's destruction to make sure Supergirl's past self survives an attack on her life and leaves Krypton.
- Supergirl is sent to Krypton's Great War to prevent the clones from dealing a heavy blow to Krypton's infrastructure.
- Superman must go back and stop H'El at the exact moment of his success. He does, but leaves him in a temporal loop at the core of Krypton that prevents the planet from dying from its fate of natural causes. It doesn't seem to change the present, but for a moment, Krypton appears in the present before disappearing.
- Space Station: One of these is in the orbit of Krypton and is programmed to attack enemies of the state.
- Super Family Team: For the first time in The New 52, Superman, Superboy and Supergirl work together without playing catch with the Conflict Ball.
- Take a Third Option: During the final issue, Superman believes he can save the timeline without having to ensure Krypton's destruction, even though Jor-El says it is impossible. Also, Jor-El wants to kill H'El, but Superman instead uses H'El's unstable Time Master powers against him to trap H'El in an infinite time loop. After H'El is defeated and Superman and Supergirl return to Earth, Krypton briefly returns to life in the present before disappearing.
- Teeth-Clenched Teamwork: Supergirl is less than thrilled to be working with Superboy, though it doesn't stop her actually saving his life as noted above under Beat the Curse Out of Him. She also mourns his death along with Superman upon getting the news.
- Terminator Twosome: H'El goes back in time to save Krypton while Superman and the gang are trying to stop him.
- Time Crash: H'El's temporal alterations cause a time tsunami, a storm that can destroy an entire star system. If the Superman family does not stop H'El, the time tsunami will destroy the Omniverse, the collection of all different universes both within and outside of The DCU.
- Time Master: The Oracle opens three portals so that Superman, Superboy and Supergirl can travel to different points in Krypton's history. Meanwhile, H'El can exist in multiple timelines at once. After Jor-El weakens him with a special gas, H'El loses control of his powers and Superman traps him in an infinite time loop.
- Used to Be a Sweet Kid: Kara, with Superboy noting that the version he meets prior to Krypton's destruction is much friendlier and sweeter than the one he met on Earth, even seeming to flirt with him a little. He wonders what happened to her... then realises that her entire world dying is the sort of thing that would sour a person.
- Walking Shirtless Scene: H'El.
- We Hardly Knew Ye: Faora. H'El kills her at the end of the arc's first issue.
- You Are What You Hate: H'El has repeatedly expressed the prejudice Krypton has for clones as savage abominations, only to learn that he himself is a Mix-and-Match Man sourced from various kryptonian species. He does not take it well and decides to save Krypton to oppress it.
- You No Take Candle: The clones during the Great War talk this way.
