WARNING: The following article contains major spoilers for Avengers: Infinity War, in theaters now.
When you're as powerful as Thanos, there aren't many times when having backup is necessary. Sure, having henchmen to do the grunt work comes in handy, but it's rare for someone to be on equal standing with a villain of the Mad Titan's caliber. In Avengers: Infinity War, the Black Order, also known as the Children of Thanos, do their master's bidding, with Corvus Glaive, Proxima Midnight, Ebony Maw and Cull Obsidian serving as imposing foes for the heroes of the Marvel Cinematic Universe as they help to retrieve the Infinity Stones.
However, there's one character who, surprisingly, aids Thanos more than the four members of the Black Order combined, but he's one of the good guys: Chris Pratt's Star-Lord.
That, of course, should come as a shock to fans of the Guardians of the Galaxy films, as the team of cosmic misfits is the sworn enemy of the Mad Titan. Surely, the only way Peter Quill would side with Thanos is through some kind of mind control. Alas, Infinity War shows that's not the case, with Star-Lord allowing Thanos to gain the upper-hand against a small, but powerful, group of heroes.
The scene in question unfolds during the latter part of Infinity War as Iron Man, Spider-Man, Doctor Strange, Star-Lord, Drax, Mantis and Nebula take the fight to Thanos on his home world Titan. Before the big confrontation, Doctor Strange uses the Time Stone to take a peek into the future in order to glimpse all possible scenarios, with only one of millions resulting in a victory for the heroes. Although it's not depicted onscreen, we can assume the heroes' plan comes from Strange's journey, because of how they get the drop on Thanos. When you take into account that many of these characters have never worked together before, they certainly function like a well-oiled machine as they subdue the Mad Titan and attempt to remove the Infinity Gauntlet. But then Star-Lord screws up everything.
Before his big blunder, Infinity War reminds viewers of the flirtatious relationship between Peter Quill and Gamora (Zoe Saldana), Thanos' adoptive daughter. When Thor warns the Guardians that Thanos has the Power and Mind Stones, Gamora forces Star-Lord to make a promise to her: that no matter what happens, he'll do the right thing and kill her before allowing her to become Thanos' prisoner again. The two might have sealed an agreement with a kiss, if not for Drax interrupting them.