History
Long ago, there was a vast multiversal war. Countless unique timelines battled each other for supremacy, nearly resulting in the total destruction of everything. But then, the all-knowing Time-Keepers emerged, bringing peace by reorganizing the multiverse into a single timeline, the Sacred Timeline.
Now, the Time-Keepers protect and preserve the proper flow of time for everyone and everything. But sometimes, people veer off the path the Time-Keepers created and this is called a Nexus Event. These people that veer off are called Variants, different versions of one certain person from another timeline, and their action in setting a new timeline would cause a possible multiversal war, if left unchecked in being restored back to the Sacred Timeline.
To make sure another multiversal war won't happen by Variants, the Time-Keepers created the TVA and all its incredible workers. The TVA has stepped in to fix the mistakes and set the proper time back on its predetermined path by resetting the timeline, with reset charges, a device that is capable of pruning the branched timelines that tries to get away from the Sacred Timeline.
If a nexus event branches past red line, which symbolizes way beyond the Sacred Timeline itself, on the TVA's scale sensor of monitoring timelines for any variance energy, the TemPad, the TVA can no longer reset a nexus event and would cause the destruction of the Sacred Timeline and the collapse of reality from a multiversal war. It is still unknown on how things will all end as the Time-Keepers are still currently working on it. When everything is finished in time, so is the TVA, since there will be no more Nexus Events. It will just be order and peace at the end of time.