There is a powerful entity, omniscient, omnipotent and omnipresent that came into existence since Big Bang. The entity do not interfere with the order of the nature but to observe it unwinds in the never ending river of time, problem is this being can move both forward and backward in time simultaneously by will. The entity had already experienced an event that took place billions of years in the future, one day the being visited Earth and noticed an amusing thing. People record events that took place and even list down things to be accomplished in the future, since the being can simply experience the actual event repeatedly at any moment why would the entity records it down in black and white? Timeline branches when the the entity intervene which is problematic and something to be avoided at all costs.
For someone else
If an omnipotent being took pity on someone who was dying alone, it might answer questions they had, if it knew they would not survive to tell anyone. It might be boring to stick around and personally explain things, so it might simply write all the answers down for them instead.
Or maybe, it isn't pity that inspires it, but scorn. Someone who thinks themself important offends it, so it chooses to show them just how insignificant they are.
This is difficult to answer because based on your description, your entity is neither omniscient nor omnipresent. Some quick answers are:
- Out of boredom
- Because when it does intervene, it's easier to explain the past by writing it down than by reciting it all over again
- To construct a lie or be malicious (eg, I'm all-knowing and I wrote down history as it happened. X happened - even though X never happened)
If the entity were omnipresent, then the being would not have "visited Earth", because it would already be in, around, and through the earth. The being would not "move" forward and backward in time by will, because it would be in all time.
If the entity were omniscient, then it would not have "noticed an amusing thing" - it would already know. And if it has the ability to learn new things (and from a human, no less), then is it really omnipotent? If it learns, does that change how it thinks or interacts with the universe?
This may seem nit-picky, but it's important. It's entirely unclear what your being is, let alone how it might think or perceive the universe, so it's not clear how to go about dealing with it's perspective on things. For example, you mention timeline branches - if the being is omniscient then why would intervening be problematic and something to be avoided? (a) what are the timeline branches - splits in the universe itself, or just the being's knowledge of how it's interaction changes the future? and (b) if it's omniscient, then it already knows when and how to intervene, which creates a self-circulating problem: all future is already known and dictated (at least in part) by it's intervention.
I'd encourage you to spend more time defining what exactly this being is or is not, and what it's motivations are.
The being is immortal, omnipotent and omniscient, yes, but it forgot to make itself immune to some things.
Now, due to Divine Alzheimer, the being forgot how to heal itself. It also keeps forgetting what happened or will happen, sometimes with hilarious results.
"I hope I haven't forgot the new universe in the oven. Last one had all intelligent beings arguing whether it would expand forever before it burst into a bajillion pieces!"
Hence it needs to leave itself postit notes on the refrigerator door.
An Omniscience prevents the being from understanding a concept of ignorance. That could be one of the goals - not to know everything. To catalogue things would let the being to divide them on two categories, recorded and not, though both are known. Then it would announce the recorded known things as new known and those not recorded as the new unknown things. Than it would stop recording and in this way become ignorant, which is a goal. In the same way it can become partially present and occasionally potent. The being remains omni-everything, but understands the limitation and that fact says to it that there is a world where even the recording of things would not change their status as known, so deeply known they are there. Though, the being's knowledge is all-inclusive it is shallow as it is possible to make it limited. At this spot it can even be killed and this is, honestly, its main concern. That is why the being needs to try to record a history- to see if it is not able to do it. If it is not able to do it then it is safe. It makes an omnipotence a problem, but it'll take care of it later...
Inspired by "Timeline branches when the the entity intervene which is problematic and something to be avoided at all costs", assume the entity is exclusively omniscient in the current timeline.
With its interventions, timeline changes, past remains the same, future-to-be is no more, and is "forgotten" by the entity, something which is known by it.
So the entity keeps track of the futures which are to be no more because of its intervention. Been omnipotent as well makes it easy, just a snap of the fingers and all the future which is going to dissapear because of a planned intervention is added to a massive library present at the start of all time, so early in time it is safe from timeline modifications.
I was thinking the library could have the most advanced technologies from a thousand timelines at its disposal, but it does not really matter, can be mega-billions of papyrus floating in deep space and preserved from decay by the entity's omnipotency, given the entity's omnisciency they just need to be there for it to be aware of their contents, no indexing mechanism needed.
Why to do it at all? Maybe the entity is amused by this gap in its omniness and records everything to find an explanation, or to fill the gap in omniscience as a compulsion, maybe it feels guilt for the futures erased from existence and has a romantic drive to keep proof of their past existence.