Paratemporal insertions

The entry to or exit from a universe's timestream by a creature or entity not native to it. Such entries / exits are assumed to be from a more senior reality, or a universe with a greater number of timespace dimensions than the one being entered or exited.

Supradimensional entities like the Powers that Be routinely pass through our timespace by way of paratemporal insertions, so that they can spend (or seem to spend) years here, while always able to return to their own timespace in the equivalent of a few seconds or minutes. To them, the "locked-in" time and space of a given universe is like just one more of many rooms in a house: they can walk into it and out of it again at will, and (if it has numerous doors) can enter it by one door and leave it by another as many times as they like.