It could be someone completely new, a character created just for this fanfic. Maybe he's a normal villager who has a kind heart and fell in love with Sakura when he saw her helping people in the village. He doesn't have any ninja powers but he has a great sense of humor and that's what attracted Sakura to him.
Well, it's hard to say. It could be that the characters or plot elements in the X Sidon comic somehow relate to the concept of lemon. Or perhaps there's a visual or metaphorical connection. But without more context, it's difficult to be precise.
There were many versions of The Animal of Sidon, and the unadapted version might be:
1 The Xerofactor
2. The Cat in the Hat: Although this version also has an adapted storyline, its original author is HP Lovecraft, not Carl Aldern Rex.
3 The Secret Life of Walter Mitty: This version also has an adapted storyline, but the original author is George Orwell.
It should be noted that there may be some differences between these versions, so it is impossible to determine which version is the absolute original version and the version without adaptation.
You can also try FanFiction.net. It's one of the oldest and largest fanfiction platforms. Just use the search function and type in 'Link x Sidon' to see if there are any relevant stories. Additionally, some Zelda - specific fan communities or forums might have links to or even host their own fanfictions of this pairing.
I'm not sure specifically about a large quantity of Link x Sidon fanfiction. However, you can start by checking popular fanfiction websites like Archive of Our Own. There might be a decent number of stories featuring this pairing depending on the popularity of the characters within the fan community.
It could be Hinata. In the original series, Hinata has a deep affection for Naruto. In a fanfiction, it would be a natural progression for her to be his secret fiance. Maybe they got engaged secretly to avoid some political unrest in the village.
One approach is to create situations where they rely on each other. Maybe there's a dark magic that is affecting both the elven land and the Zora domain. They have to work together to find the source and stop it. During this time, they see each other's determination and courage. Also, have them communicate their feelings honestly. If the sun elf is feeling homesick, Sidon could comfort her, and this vulnerability would bring them closer.