Soooo what if the Sky People were actually from the Realm, and were actually a group of ancient entities that controlled the sky and the Steves had to appease them every so often and stuff-

The Sky People would be in charge of and control the sky, as previously mentioned. They control the weather, how it looks, when things happen with it (like rainbows), basically anything related to the sky is their turf. If someone wants to have a certain weather or something happen, they could offer something to the Sky People at one of the mountains dotted around the Realm that act like connecting temples. However, the Sky People can reject the offer even though the person made the climb up one of the mountains to the temple at the top, although that means they reject the offering too.

A lot of stories are told about the Sky People in this AU. Some tell that the Sky People gave the Steves the ability of lightning. Others say they came before Origin himself. However, there's one that's been known to be entirely true;

The Sky People can choose a 'guardian' of sorts. It happened a few times, in very ancient battles that lasted centuries, the last one being during the fight that sealed the First Curse in the Armor. The Sky People played a huge part in sealing him, given how they had otherworldly abilities to craft powerful things, and made the Armor.

However, making something that had to seal something so powerful for so long had drained their power. Since then, the Sky People barely interacted with the Realm itself, although still did their job of maintaining the sky. This drain also meant they could not choose a guardian for a very, very long time.

Centuries passed. The Steves still interacted with and gave offerings to the Sky People, whether to convince them to do something or just to appease them when something sets them off. They were mostly peaceful, minus the few times where somebody screwed up bad enough to invoke their wrath.

And then Sabre arrived.

Now, this part can happened pretty much anywhere in the story. Could be the very beginning, could be after Rainbow gets his powers, could be an after-the- main-story thing, whatever. The thing is, Sabre immediately gets the Sky People's attention. And given how they've finally gotten their power back, you can guess what they do. A cool idea would be that the Sky People choosing him became why Sabre is known as The Catalyst.

What pretty much happens is that the Sky People contact a Steve that was visiting their main temple, telling them to bring Sabre over there. Sabre's friends (depending on when this is in the series) would go with him, a bit worried since it's been a very long time since the Sky People have wanted a specific person. When he gets there, the Sky People basically just point at him  and go

"This one. We want this guy."

And suddenly Sabre's been chosen by a bunch of ancient eldritch entities to be their guardian in the Realm.

Cue confused chaos from literally everyone else.

Maybe Sabre gets powers immediately after he's chosen, maybe it takes a while for them to adjust to him and grow, but there has to be something in it for Sabre so he does get some kind of power from the Sky People.

Anyway, here's some funny situations because

—

(Sabre doesn't know about the Sky People yet. The day is normal, when suddenly the sky turns dark grey and there are thundering noises everywhere.)

Orange: Ah crud, the Sky People are ticked off.

Sabre: (Very confused and probably in fight or flight mode) The Sky WHAT are angry-

—

(Sol trying to give his speech and throw shade at Sabre, when like ten lightning strikes happen veeerrryyyy close to him.)

Sky People: (As a loud, booming voice coming from the general direction of the sky) F*** OFF.

Sol: (Just standing there at the podium like a moron out of fear)

—

(The Sky People probably got bothered by a lot of people trying to cause chaos with the weather, right?)

Sky People: (At Dread) For the last time, we're not making it storm in the desert so you can "watch the Desert Steves panic". That's not a prank, that's attempted genocide.

Sky People: (At Nightmare) Why on Earth would we- Causing a drought everywhere except your kingdom so people have no choice but to join you is plain stupid.

Sky People: (At Void, before he even opens his mouth) Nah uh. Turn around and walk right back outta here and save yourself the trouble. Whatever you're about to say will get you smote.

—

(When Sabre gets killed by Nightmare that one time. Insert absolute chaos as the Steves see the Sky People enraged like never before.)

—

TFC: (Changes what the sky looks like during his big event)

Sky People: ExCUSE you-

—

(Imagine the Sky People just change the weather to what Sabre wants because)

Sabre: (Looking out the window at a hot, sunny day) Ah dang. Kinda wish it would rain so it'd cool off.

(Sabre turns around for like two seconds, and when he looks out the window again it's suddenly pouring outside.)

Sabre: ...What the frick.

—

Have fun with that :D