The six Avengers recruited from various times to protect Rick Jones awake to find themselves in an alternate future confonted by the Galactic Avengers Battalion and their leader Jonz Rickard from #1. Captain Marvel realises that the Battalion perceive them as the rebellious Guardians of the Galaxy.
They are captured, but then rescued by Immortus and their 7th member Yellowjacket, who admit to abducting the Avengers in #8, and that Yellowjacket used the powers of Limbo's insects to make them seem like the Guardians here. Immortus wanted Avengers to see the kind of future he was trying to prevent by stopping Rick Jones accessing the Destiny Force, if necessary by killing him.
Immortus takes Avengers to see the 3 Time-Keepers. They explain that they were created at the end of time by He Who Remains, to carry knowledge into the next universe. In some alternate realities the 3 destructive Time-Twisters were born instead. They hint that Immortus sometimes worked for Time-Twisters instead of themselves. The Time-Keepers strive to ensure that the alternate realities all culminate in their own birth rather than that of the Time-Twisters. Part of that manipulation is ensuring that humanity doesn't expand to infect the galaxy and beyond. As usual this is a brief version of a complicated history. Once again I'll include the more detailed version here rather than in the Notes section.
We met the 3 Time-Twisters in Thor #243-245, where they were moving backwards in time to the beginning of the universe, devastating every world they touched. They visited Earth every 3000 years. They had destroyed the 80th century. Zarrko came to recruit Thor's help saving 50th Century Earth, and in doing so stop them from reaching 20th century. Thor went to Time-Twisters' source in the Citadel at the End of Time, where he found He Who Remains, the last sentient being in the universe, who was about to finish creating 3 beings to carry knowledge to the start of the next universe. When Thor convinced him that his creations would instead destructively travel back to the start of this universe, he abandoned his plan. Thor returned to a reality in which the Time-Twisters didn't exist.
In Thor #282 Immortus said 3 beings from the end of time made him custodian of the 7 millenia he occupied as Kang. They weren't named then, but they were called the Time-Keepers when Immortus repeated the story a decade later in Avengers West Coast #61. Time-Keepers made their first actual appearance in AWC#62.
In a series of AWC issues leading up to this, Immortus had chosen Scarlet Witch as a nexus being to convert to a source of power to safeguard the events leading to a future the Time-Keepers wanted to protect. The Witch broke free, and the built-up power threatened the multiverse. Time-Keepers froze Immortus and stored the power in him, to preserve their own future.
In Quasar #30 Watcher explained Time-Keepers were born from eggs at end of universe in same way Time-Twisters were. They gave Watcher the power to see alternate realities.
Time-Keepers/Twisters played a major role in the TimeQuake story in What If v2 #35-39.
#35-36 explained that the timelines Immortus had been culling for the Time-Keepers, as seen in various issues of AWC, contained dangerous nexus beings. The power of the deleted nexi was channeled into Scarlet Witch, and Immortus had hoped to use her to challenge Time-Keepers, which was another reason they had frozen him.
Unfortunately he had missed 4 nexi. What If v2 #35-38 showed Time-Keepers trying to eliminate these nexi, opposed by Immortus's astral self under the name Whisperer. They failed to destroy 3 of the 4 nexi. In #38 Time-Keepers vanished into non-existence, freeing Immortus who gained power over the multiverse. #39 said Immortus gained this ultimate power by adding the last 4 nexi (even the elimated one?) to his store. It also revealed more about the origins of Time-Keepers. He Who Remains was the last director of the Time Variance Agency. After his failure with the Time-Twisters he created the Time-Keepers. Now Watcher and TVA changed the 30th Century Nathaniel Richards so that when he became Immortus he was unable to store the nexus power, and Immortus exploded. 2 sets of Time-Keepers now reappeared. One set turned out to be Time-Twisters in disguise. It transpired there are 2 parallel end-of-universes vying for dominance. Time-Twisters tricked Immortus into the Scarlet Witch fiasco in AWC in order to bring about their version of end-of-universe, and it is they who we have been following in TimeQuake. Now they reverted to eggs, and the true Time-Keepers regained dominance.
Immortus next popped up in the Terminatrix backup in Avengers Annual #21, without saying how he survived. Here in Avengers Forever #10 the Time-Keepers casually mention that they 'remade' him.
Time-Keepers next appeared in Avengers: Terminatrix Objective #3, and that brings us to Avengers Forever.
Now Immortus describes how he manipulated timelines for the Time-Keepers to keep humanity from spreading out into the galaxy with Rick Jones's Destiny Force. As well as deleting the 50's Avengers timeline, as shown in #5, he persuaded the 'Martians' and Badoon to invade Earth in various alternate realities. Time-Keepers remind Avengers that humans are so dangerous they have even defeated Galactus, Celestials and Infinites.
Time-Keepers and Immortus intend to destroy all but a few of the timelines with humanity in. Yellowjacket regrets the deal he made with Immortus in #8, and uses the Limbo insects to free the other Avengers by giving them temporary access to the Destiny Force. He has also sent insects for help, which arrives in the form of Rick Jones, Kang and the Kree Supreme Intelligence.