Gamora

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.

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 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 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.

Does Gamora come back to life? No. The Gamora who died on Vormir is permanently dead; the Soul Stone sacrifice is irreversible.

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.

Guardians of the Galaxy Vol. 3 (FILM, 2023) — Rocket's origin: created by the High Evolutionary, who tortures and discards animals in pursuit of perfection. The team destroys him and frees his experiments. The team then disbands and reforms — Rocket becomes captain with Groot, Kraglin, Cosmo, Adam Warlock, and Phyla; Quill goes to Earth to meet his grandfather; Drax and Nebula stay on Knowhere raising rescued children; Mantis leaves to travel; Gamora returns to the Ravagers.