@Vree
See, I always had an idea that I never could quite fit into a story cause I doubt anyone really wanted to hear someone’s ramblings on how they’d woo a fictional character via self-insert, but the way I always pictured it happening.

Dreamy Daze, wanting to get away from Rainbow Dash hounding him about working, hopped on a cloud and closed his eyes, letting the wind carry him wherever. Luckily for Dreamy, fluffy clouds on a blue sky was a natural camouflage for him.

When Dreamy finally awoke from his nap, he found that he had been taken all the way to Canterlot, and what’s more, he was right near the castle’s towers, and found himself looking at the half-confused, half-amused face of Princess Celestia. The barely-awake Dreamy said the first thing that came to his mind.

“Oh hey Celestia.”

No instant groveling at her hooves, no immediate panic to try and bow in her presence, not even addressing her by her royal title.

The two eventually struck up a lively, friendly conversation, speaking like a pair of old friends despite just meeting that moment.

It had to be cut short however, as Celestia had to get to another boring royal meeting, but she thanked Dreamy for the brief distraction, and hoped that she’d see him again sometime soon.

Satisfied with his quick nap and chat, Dreamy headed back to Ponyville, not thinking much of the encounter.

At least, not consciously thinking of it. Over the next few days and weeks, Dreamy kept good on his word, sneaking out of work or spending his free time cloud-riding to Canterlot, striking a friendly chat with Celestia, and then leaving.

Dreamy always talked to her not as a princess, but as Celestia. Sure the topic of royal business and what Dreamy would do if he were an alicorn would come up in conversation, but it was always kept casual, never with the stuffy, formal tone that one should take when talking to royalty.

And brief as they were, Celestia enjoyed talking with Dreamy whenever he could come by. It was always a pleasant and needed break between the busy life a princess demanded. He was somepony to confide in, to vent to, to gossip with, to just talk normally with.

After one meeting in particular, Dreamy promised to meet her there at the tower again tomorrow before the two had to part ways.

Once he got back to Ponyville, he was quickly confronted by Flicker Feather, who noticed that Dreamy had been seen much less frequently around his hometown, and would sometimes spot a lone cloud that would float to Canterlot, and then spot a cloud coming all the way back.

It didn’t take much interrogation, Dreamy revealed what he’s been doing, stating that it was no big deal.

“Rainbow Dash has been on my ass trying to figure out where you disappear to all because YOU’VE been crushing on Princess Celestia!”

Crushing? That’s ridiculous! Dreamy didn’t have a crush on Celestia. He just enjoyed talking to her, and made more frequent and longer visits in order to see her, and liked making stupid jokes in order to make her laugh, and always felt warm and fuzzy inside when spending time with her-

Oh no.

Still, he made a promise, and so the next day, he went to go see Celestia. Though now that he was painfully aware that he was crushing on royalty, the cool and collected pegasus turned into a blushy, nervous wreck.

The change in behavior made Celestia very confused. Something clearly happened to Dreamy to make him so worked up, though despite her asking, Dreamy denied anything was wrong.

Celestia insisted on finding out with a few pokes to the pegasus’s sides to prod him into revealing more. And when a few squeaky giggles came out, she decided she needed to be a bit more thorough in her questioning.

There’s no way Dreamy could just tell Celestia he had a crush on her. If she found out, she’d totally cut off all communications with him. There’s no way she’d reciprocate his feelings.

Turns out, Celestia loved “embarrassed and squirmy Dreamy” just as much as “relaxed and carefree Dreamy”.

So I don’t know if there is anything as far as “canon” but I imagine it like:
Dreamy was just a lazy (young hunky) pega’ who enjoyed floating around his cloud, chilling (also a good hiding spot from anyone searching for him to do his job)
He frequently floated by the castle and would wave at a certain lonely princess busy at work. It became sort of a habit and the visits got…longer and more intimate
It’s ideal because Celestia is worried about others knowing about her affair with a pony like, 1/50th her age but Dreamy can drop by and leave without anypony noticing
Of course, the scandal is now known as a rumor by tons of ponies (though works well as far as preventing any photos or confirmation by news sheets) partly thanks to Luna’s nosiness who has her opinions about her sister’s cougar escapades
High-ranked nobleponies in the royal court dispathed the captain of the guard himself to guard the doors of the royal chambers to prevent entry and arrest any ruffians trying to compromise the princess
Shining Armor’s been reporting back that “all is well”