Warning: The following contains SPOILERS for The Sandman season 1.
A nightmare sequence in The Sandman episode 3 centers around the magician Johanna Constantine and a girl named Astra. The details of the bad dream are not explained beyond it being a recurring nightmare of something from Johanna's past. Fans of the comic book character John Constantine, however, are well aware of who Astra is and the significance of Johanna Constantine's nightmare.
The character of Johanna Constantine in The Sandman has been a source of some confusion in Netflix's adaptation. When the first wave of casting announcements listed Jenna Coleman as a character named Johanna Constantine, it was presumed she would be playing the role of Lady Johanna Constantine, who in the comics was an ancestor of the warlock John Constantine from the time of the French Revolution. It was later revealed, however, that in Netflix's The Sandman series, Coleman plays both the Lady Constantine and a new character based on John Constantine named Johanna Constantine.
While this change might seem arbitrary, it was necessary due to the live-action character rights for John Constantine being tied up in J.J. Abrams' reboot of the Constantine TV series. However, fans of the Hellblazer comic series can take comfort in the fact that The Sandman episode 3 is packed with Easter eggs paying homage to the source material, even as it establishes Johanna Constantine as the John Constantine of this universe through her recurrent dreams of Astra.
Johanna Constantine's Nightmare Explained
The nightmare that opens The Sandman episode 3 reenacts the Newcastle Incident. First depicted in Hellblazer #11, the Newcastle Incident set a young John Constantine on the road to Hell after he and a group of friends (collectively known as the Newcastle Crew) tried to banish a demon that had been released by a botched summoning executed by club owner Alex Logue. This same incident with the Newcastle Crew set up the story of the Constantine series and was later referenced in Legends of Tomorrow. While John was able to send the demon back to Hell, he was unable to prevent it from grabbing Alex's young daughter, Astra Logue, and taking her into Hell with it.
The same thing occurs in The Sandman episode 3, though Johanna Constantine is working alone rather than as part of a group of amateur occultists. The end result is the same, however, with both John and Johanna left clutching the severed arm of the innocent girl they've failed to save from the forces of evil. This results in years of continually dreaming of Astra being sucked into Hell until Dream of the Endless agrees to stop the recurring nightmares as repayment for their aid in recovering the pouch of sand that, with The Sandman's ruby and helm, was the source of his power.
What Happens To Astra In DC Comics
In the comics, Astra Logue remained trapped in Hell until the end of the Critical Mass storyline in Hellblazer #96. The story pit John Constantine against the demon lord Buer, who ruled over all the innocent children that had ever been claimed by Hell. With a little unwitting help from Aleister Crowley, John was able to outwit Buer and win the freedom of every child in Hell, including Astra, allowing them to go to Heaven.
A drastically different fate awaited Astra Logue in the Arrowverse, where she grew to maturity in Hell and became a demon in her own right. She became one of the villains of Legends of Tomorrow season 5, joining forces with the Ancient Greek god Fates to end free will across the multiverse. In the end, however, Astra saw the light and joined forces with the Legends, helping John Constantine to regain his soul in the process.
Will Astra Return In The Sandman?
It is highly unlikely that Astra Logue will have any further appearances in Netflix's The Sandman. The character never appeared in the original The Sandman comics, although John Constantine's appearance in The Sandman #3 did make reference to his recurring nightmares of the Newcastle Incident and how he lost Astra to Hell. John Constantine also did not have any extensive appearances in later issues of The Sandman, apart from a cameo in a crowd scene, so it seems improbable that they would take the time to resolve this story for Johanna Constantine in Netflix's The Sandman when it was not part of the original source material and would be better suited to a spinoff focused on her character. While it's possible Astra might make an appearance in one of the later episodes of The Sandman season 2 set in Hell, it would be an odd Easter egg, to say the least.
The Sandman season 1 is now streaming on Netflix.