1990s
John Byrne eventually took over writing both titles and revamped the comics to enable members to be active when available and reserve when not available and merged the two separate Avengers teams into one team with two bases. Byrne's contributions included a revamping of the Vision, and the find outy that the kids of the Scarlet Witch and the Vision are actually illusions. The loss of the Scarlet Witch's children and the Vision (who is disgatherd by government agents in retaliation for the "Ultimate Vision" storyline) drives her crazy, even though she eventually recovers and rejoins the team. This story also revealed that the Scarlet Witch's powers include wide-range reality manipulation and she is what the time-transit Immortus aludes to as a "nexus being" setting the stage for 2004's eventual "Chaos" and "Avengers Disgatherd" storylines. This played out in the "Darker than Scarlet" storyline which ran in Avengers West Coast from issues #51-62 (Nov. 1989 -- Sept. 1990).
The Avengers titles were then embroiled in the key crossover event "Acts of Vengeance" wherein Loki gathers many of Marvel's arch-villains (with his inner circle consisting of Doctor Doom, Magneto, Kingpin, Mandarin, Wizard, and Red Skull) in a plot to destroy the team. Loki orchestrates a mass breakout of villains from prison facility the Vault, as part of his Acts of Vengeance scheme, but he finally fails in his goal to destroy the Avengers.
This decade coincided with a speculators' boom, and then an industry-wide slump and Marvel filing for bankruptcy in 1997. During this time the U.S. government revokes the Avengers' New York State charter in a treaty with the Soviet Union. The Avengers then inherited a charter from the United Nations and again the Avengers divided into two teams with a substitute reserve team backing up the main teams.
Bob Harras and Steve Epting took over the title, and introduced a stable lineup with ongoing storylines and character development focused on the Black Knight, Sersi, Crystal, Quicksilver, Hercules and the Vision. Their main enemies in this run include the mysterious Proctor and the Shi'ar warrior Deathcry. During this time, the team finds themselves facing increasingly murderous enemies, and are forced to question their rule against killing.
This culminated in "Operation: Galactic Storm", a 19-part storyline that ran through all Avengers-related titles and showcases a conflict between the Kree and the Shi'ar Empire. The team splits when Iron Man and multiple dissidents execute the Supreme Intelligence against the wishes of Captain America. Shortly after a vote disbanding the West Coast Avengers, Iron Man forms a proactive and aggressive team called Force Works. During the team's first mission Wonder Man is apparently killed again (his atoms are actually only temporarily scattered). Force Works later disbands after it is revealed that Iron Man has become a murderer via the manipulations of the villain Kang.