Thanos

In 2018, Thanos erased half of all life in the universe. Five years later, in 2023, the survivors reversed it. The vanished returned — the same age they'd been, having experienced no time at all. Everyone else had aged five years.

• The Infinity Saga = Phases 1–3 (2008–2019). Villain: Thanos. Object: the Infinity Stones.
• The Multiverse Saga = Phases 4–6 (2021–2027). Villain: originally Kang, now Doctor Doom. Object: the multiverse itself.

Thanos, meanwhile, is a Titan. His homeworld collapsed under overpopulation and resource exhaustion. He proposed killing half the population at random to save the rest; he was called a madman; the planet died anyway. He concluded he had been right, and spent the following centuries applying the solution elsewhere.

Loki does not die. He falls into the hands of Thanos, who gives him an army and the Mind Stone.

Post-credits: the first appearance of Thanos.

The Aether is handed to the Collector for safekeeping, since keeping two Stones in one place is unwise. Thanos will take it from him.

He does not support Thanos. He accepted the Aether for safekeeping fully intending to add it to his collection, which is exactly what a collector would do.

Thanos takes it by force — and the scene the audience watches of Thanos torturing him is an illusion. Thanos already had the Stone, and had already killed him.

Peter Quill steals an Orb containing the Power Stone. Pursued for it, he ends up in a prison with Gamora (Thanos's adopted daughter, defecting), Drax (whose family Thanos's forces killed), Rocket (a genetically and cybernetically tortured raccoon), and Groot (a tree). They escape, sell out, un-sell out, and stop the Kree fanatic Ronan the Accuser from using the Stone to destroy Xandar. Groot dies saving them and regrows from a cutting as Baby Groot. The Stone is left with the Nova Corps.

Nebula, Gamora's sister, mutilated repeatedly by Thanos as a punishment for losing to Gamora in combat, begins a slow turn from villain to one of the most important characters in the saga. Mantis joins the team.

When does Nebula actually join? Not in these films. She's an antagonist in Guardians working for Ronan, and flies off at the end. In Vol. 2 she's hunting Gamora for revenge, then reconciles when Gamora explains she never wanted their father's contests either — and leaves again to hunt Thanos.

It fails. Between films, Thanos attacks Xandar and takes it offscreen; a news report early in Infinity War is the only acknowledgement.

Thanos acquired it before 2012 and gave it to Loki inside the scepter to fund the Chitauri invasion, expecting both it and the Tesseract back afterwards. Loki failed; the scepter went to S.H.I.E.L.D., then quietly to HYDRA, who used it on the Maximoffs.

The Avengers do not reassemble before Thanos arrives. That is the point of this film.

Thanos, with the Black Order, collects the Stones. He already has Power (taken from Xandar, offscreen). He takes Space from Loki — and kills Loki, and Heimdall. Thor is left drifting; Hulk is beaten so badly that Banner cannot summon him again for the rest of the film.

Was Loki ever on Thanos's side? He was coerced, not allied. The Avengers shows him visibly unwell and under pressure; Infinity War confirms it when Thanos reminds him he was given an army and a Stone and failed.

The Black Order — Thanos's four adopted enforcers, also called the Children of Thanos. Ebony Maw (telekinesis and manipulation; blown into space by Stark and Parker), Corvus Glaive (killed by Vision), Proxima Midnight (killed by Wanda), Cull Obsidian (killed in Wakanda). All four dead by the end of the film; the 2014 versions return briefly in Endgame and die again.

Sequence of acquisitions: Power (Xandar — the attack on the Nova Corps happens entirely offscreen between films, acknowledged only in a passing news report), Space (Loki), Reality (from the Collector, in a trap), Soul (Vormir — the Stone requires the sacrifice of someone you love, so Thanos throws Gamora off a cliff), Time (Strange gives it to him voluntarily to save Stark's life), Mind (torn from Vision's head).

How does Wanda destroy the Stone, and how does Thanos undo it? Vision spends the film begging her to do it, arguing one life against half the universe. She refuses until the last possible second, then holds off the entire battle with one hand while destroying the Stone — and Vision — with the other.

Thanos then uses the Time Stone to reverse the last few seconds locally, restoring Vision intact, and rips the Stone out of his skull while he's alive and conscious.

How does Thanos force Strange's hand? On Titan the team nearly wins — Mantis has him sedated, Parker is pulling the Gauntlet off — until Quill learns Gamora is dead and punches him awake. Thanos then drives a piece of Stark's own armour through his abdomen and holds him there. Strange, who spent the film insisting he'd let both Stark and Parker die first, hands over the Stone.

What species is Thanos, and why is he so strong? A Titan — an Eternal from the moon Titan.

Thanos snaps his fingers. Half of all life in the universe disintegrates. Among the dead: Bucky, Wanda, T'Challa, Groot, Drax, Mantis, Quill, Strange, Sam Wilson, Peter Parker, Hank Pym, Janet van Dyne, Hope van Dyne, Nick Fury, Maria Hill.

Thanos retires to a farm. He wins.

Twenty-three days after the Snap, Danvers locates Thanos on a remote planet. He has already used the Stones a second time to destroy the Stones, so there is nothing to undo. Thor beheads him with Stormbreaker, on the spot, in about three seconds. It accomplishes nothing, and the guilt of not aiming for the head the first time is what breaks him for five years. The film jumps forward.

Scott Lang escapes the Quantum Realm — five hours for him, five years for everyone else — and realises time works differently down there. Stark cracks the physics. They mount a time heist: teams travel to past moments to borrow the Stones before Thanos takes them.

• 2012 Rogers does not know. He thinks he's fighting a Loki illusion. Present-Rogers wins the fight by saying "Bucky is alive," which stuns him
• Howard Stark (1970) does not know. Tony introduces himself as "Howard Potts." Howard finds him oddly familiar and nothing more
• Frigga (2013) does know, instantly. She's a witch; she tells Thor she can see he's from the future and doesn't care
• The Ancient One (2012) knows, because Banner is holding the Time Stone and she can see the branch forming
• 2014 Thanos learns everything, which is the disaster

What are Nebula's neural links? Nebula is heavily cybernetic — Thanos replaced parts of her body each time she lost to Gamora in combat. Her systems are networked, which means the 2014 Nebula and the 2023 Nebula share memory access when in proximity.

In 2014, past-Nebula involuntarily accesses present-Nebula's memories and sees the Snap, Thanos's death, and the entire plan. Thanos extracts it from her. Past-Nebula then swaps places with present-Nebula and travels forward as a spy. Present-Nebula eventually kills her.

A 2014 Thanos follows them forward and attacks. The final battle assembles every surviving character in the franchise.

Tony Stark takes the Stones and snaps Thanos and his entire army out of existence, and it kills him. His funeral closes the Infinity Saga.

Didn't Thor already kill Thanos? Two different Thanoses. Thor killed the 2018 Thanos permanently at the start of the film. The one in the final battle is the 2014 version, pulled forward by Nebula's neural link — he has never snapped, never held the Stones, and is arguably more dangerous for it.

Why does Stark's snap only kill Thanos and his army? The Gauntlet does what the wearer wills. Thanos willed "half of all life"; Stark willed "Thanos and his forces." Same tool, different instruction.

The Gamora who is alive is the 2014 version, pulled forward with 2014 Thanos and stranded in 2023 when he's erased. She has no memory of the Guardians, no relationship with Quill, and finds his grief for a version of her she never was intensely irritating. Guardians Vol. 3 is largely about Quill accepting that.