@
Nekoo
: Well, the intention of my Sonic/Rosalina headcanon is to be ambiguous.
I'll go into it further now:
Rosalina is so intrigued by Sonic for a multitude of reasons:
-It started when the Lumas were telling her about how they were playing with Sonic, and enjoying his company. Anyone who is good to the Lumas is someone Rosalina is bound to like to some degree. So she had the intention of meeting up with him, and it was supposed to not be a big deal. However, she never was able to run into him in her free time. He's almost always on the move.
-Then, the Lumas started to get to know him better. They learned of his adventures, his friends, his immense passion for literature...and it all just made him sound like a really amazing person to her. The Lumas noticed, and tried to make sure to introduce her to Sonic, but cosmic duties prevented this from happening (Rosalina and Palutena are allowed to leave and come back to the Smash World at will, since they are divine figures with their own immense responsibilities. Rosalina in particular is sort of a guest of honour, since she is undeniably more powerful than Master Hand and even Master Core, and is a lady of legend that not many people know about, while Palutena is outright worshipped).
-Eventually, Rosalina went searching for Sonic of her own accord, but when she found him, he was busy training. However, she watched him from afar. She was awfully impressed with how adept he was, considering he's supposed to be just a hedgehog. He was like no hedgehog she'd ever seen.
After his training, Sonic was hanging out with Pit and Pikachu, and everything seemed very boyish about him. She figured he would not be interested in someone like her, especially since she is a really busy person, and somewhat struggles with social interaction as it is, unless she's talking to Mario, Luigi, or the Lumas.
-Rosalina eventually started trying to write stories based on what she knew about Sonic. This is not unusual for her, she often does write stories about various heroes and significant figures, for the Lumas. However, when she started to read one such story to the Lumas, they caught on to the similarities to Sonic pretty quickly. She got pretty flustered after this (something she rarely does), because she honestly doesn't know what it is.
In actuality, she is drawn to him because they have a lot in common, he possesses great power despite being a mortal, yet has such as casual and carefree nature. He's great with kids, something Rosalina adores, and he's very passionate about literature, to the same level she is, and nobody else in the Smash World is (Shulk is another exception, though he keeps his distance from Rosalina because of how she seems like a god of sorts, and he's not sure how he feels about that. He doesn't judge her too harshly though, because she acts with some humanity and seems stable).
Really I could go on developing this all day but the gist is that I believe Sonic and Rosalina would at least become amazingly close friends. Whether or not people want Rosalina to feel romantic feelings towards Sonic, or even the other way around, is up to them.