
Marvel Studios' final Phase 5 project has made history on Disney+ with its twist ending, which differs from the ending of any MCU Phase before it. Phase 5 recently concluded with the release of Ironheart on Disney+, the last project before Marvel Studios began Phase 6 with The Fantastic Four: First Steps. The final moments of Ironheart revealed a surprise team-up that leaves Phase 5 on an interesting note.
The finale of Ironheart sees Riri Williams (Dominique Thorne) meet with the demonic villain Mephisto (Sacha Baron Cohen), aka the entity who has been pulling the strings on Parker Robbins/The Hood (Anthony Ramos) all season. With the Hood out of the picture, Mephisto presents his offer to Riri instead, promising to grant her a wish in exchange for her allegiance. Riri decides to accept this offer in exchange for bringing back her dead best friend, Natalie (Lyric Ross), who was the crux of her grief all season.

The final moments see Mephisto and Riri teaming up, which marks the first instance that a MCU Phase's final title has seen that project's titular hero and villain team up. The twist leaves Phase 5 in an interesting place, and opens the door to explore the ramifications of this unlikely team-up in Phase 6 and beyond. While this is the first time that an MCU Phase-ender has employed the hero/villain team-up trope, it's far from the first Marvel Studios project to have the good and bad guys become allies.
9 Notable Villain and Hero Team-Ups in the MCU
Thor & Loki

The Asgardian brothers, Thor (Chris Hemsworth) and Loki (Tom Hiddleston), have long had a rivalry. The mischievous Loki established himself as the villain of the first Thor film after orchestrating a series of events to take the throne.
However, the brothers teamed up multiple times, first in Thor: The Dark World when Thor enlists Loki's help and frees him from prison, and then again in Thor: Ragnarok, when the brothers go on a journey to locate their father.
The Guardians of the Galaxy & Yondu

Yondu (Michael Rooker) was one of the Ravagers responsible for abducting and then raising Peter Quill (Chris Pratt), but after Quill steals from Yondu, the Centaurian puts a bounty on his protégé's head. Despite this, Yondu ends up becoming an ally to the Guardians in both the first and second Guardians of the Galaxy films, and eventually sacrifices his life to save Quill.
Gamora & Nebula

Gamora (Zoe Saldana) and Nebula (Karen Gillan) grew up with a fraught relationship as Thanos' adopted daughters. In the first film, Nebula teams up with Ronan, making her an enemy of the Guardians, but the two sisters come to a truce in Guardians of the Galaxy Vol. 2, and Nebula eventually becomes a part of the team.
Spider-Man & Mysterio

Spider-Man (Tom Holland) unknowingly teamed up with the villain of the piece in Spider-Man: Far From Home, when Mysterio (Jake Gyllenhaal), a hero claiming to be from the Multiverse, arrived to ask for his help in defeating the Elementals. A twist later revealed that Mysterio was a disgruntled Stark Industries employee who wanted to get close to Peter Parker to claim Stark's EDITH glasses.
Falcon, Winter Soldier & Zemo

An unlikely alliance formed between Falcon (Anthony Mackie), the Winter Soldier (Sebastian Stan) and Captain America: Civil War's villain Zemo (Daniel Bruhl) in the Disney+ series The Falcon and the Winter Soldier. The duo approaches Zemo for his assistance against the Flag Smashers, before the Wakandan Dora Milaje ultimately takes the villain to be held accountable for killing their king.
Loki & Sylvie

In Loki Season 1, the God of Mischief meets a female variant of himself from the Multiverse, named Sylvie (Sophia DiMartino). The two are introduced at odds with each other as Loki assists the TVA in capturing Sylvie, who has been killing their agents. However, the duo eventually teamed up against TVA.
Spider-Man & His Villains

The Multiversal plot of Spider-Man: No Way Home involved all the villains from past Spider-Man films being pulled into the MCU due to a spell gone wrong.
Spider-Man (Holland) initially allied with the villains Doc Ock (Alfred Molina), Green Goblin (Willem Dafoe), and Electro (Jamie Foxx), hoping to get them home to their universes while preventing their deaths in those timelines, but some of them return to their villainous intentions.
Ant-Man, Wasp, Cassie & MODOK

The Ant-Man family unit of Ant-Man (Paul Rudd), Wasp (Evangeline Lilly), and Cassie (Kathryn Newton) teamed up with an unlikely villain in Ant-Man and The Wasp: Quantumania. After the big-headed Mechanized Organism Designed Only for Killing (MODOK) was revealed to be none other than previous villain Darren Cross (Corey Stoll), Cassie is able to convince the subjugated villain to turn against Kang the Conquerer (Jonathan Majors) and help the Ant-Man team.
Loki & Victor Timely

After encountering He Who Remains (Majors) and learning about his variants in the Multiverse, Loki is skeptical of Victor Timely, the 19th-century inventor whose devices form the basis of the TVA. However, in Season 2 of Loki, the God of Mischief teams up with the one he fears, requiring his help to stop the Multiverse from falling apart.