I would like to point out that I'm referring to fanworks in general, and not a specific piece.
Since we don't get to know much about Jadeite in the series, his character is very free to work with. Another good thing is that he never officially died in the anime, meaning you can bring him back without too much fuss.
The easiest way to write Jadeite is to make him an idiot and/or comic relief, which saves a lot of trouble coming up with decent motives and characterization.
I'm usually not to fond of Jadeite the moron (or Nephrite the drunk, Zoisite the homicidal drag-queen and Kunzite the incredibly vain cape-man) but they can be hilarious in parodies, if used correctly. Sadly, when it comes to Jadeite, many writers, especially those that concentrate on the Sailor soldiers, never bother to flesh him out and end up making him an even flatter character then he is in the series.
Some people write Jadeite as the head tactician back in the Silver Millenium. This is quite reasonable when you look at the different ways the kings carry out their mission, since Jadeite has (in my opinion) the majority of effective and functional plans together with Zoisite. But while the second works by a snatch-and-run principle, Jeddy actually takes the time to organize and carry out quite complicated schemes. Kunzite's plans, while often very complicated, usually miss some crucial element (like why bother with the DNA, look at the hairstyle!) and I'd say he's better at planning a direct battle then these kind of undercover missions.
Sadly, once you think about how darn inflexible Jadeite is the theory goes down the drain, since one of the first thing anyone with the slightest grasp on military matters should learn is when and how to change a plan. But, lets just blame that on Metallia's brainwashing, ok?
Anyway, in this kind of fics, Jadeite is usually written as quiet, intelligent and a bit shy, and the same goes for fics where he is a teacher or something of the kind. might have something to do with his fondness for glasses, since many anime characters who wear glasses fall into the quiet, intellectual kind.
As long as you stay with "good" Jadeite (the one belonging in Endymion's court) you can write him as the silent bookworm without problems, since neither the manga nor the anime really shows how the Shitennou acted while they were on the Earth side. Nicer, probably, but beyond that...
However, when working with the Dark King Jadeite, it's a bit harder. Cruel, overconfident and prone to gloating, he doesn't appear to be shy and definitely not the kind who lives only for his research and completely ignores the outside world (the mad-professor approach still exists, of course...)
But do remember that Jadeite is ice-cold. All the time, except when Beryl yells at him, and even then he manages to stay moderately calm. Unless you drastically change some factors and make a severe remodeling to his personality, Jadeite is not the kind of person who will show emotions easily, if at all. I quote someone; "If there's one guy who's even more of an icy bastard than Malachite, it's probably Jed." Too true, so why do people think that he's the spunky, carefree kind? Or worse, the doe-eyed lover if they're writing yaoi.
This leads me in on the subject of relationships...
They are an aspect entirely to themselves. If you want to stay canon, it's strongly hinted in the manga that Sailor Mars and Jadeite were a couple, and that Jadeite still has some feelings for her. (This didn't stop her from killing him, but hey, angst fiction is always an option...)
Not that this little tidbit has stopped people from pairing him up with Usagi, Minako, Ami, Nephrite, Beryl etc.
In the anime, Jadeite hardly interacts with the other characters, leaving him free to be paired with whoever the author feel suits him, but most people seem to stick with Mars, since she's the 'original' or Usagi, because she's the main character (I'd dump Mamoru for Jeddy, no doubt about it. But that's just me)
If people want to write one of the kings a ladies man, it's mostly Jadeite or Nephrite who takes the role. By process of elimination, anything else would be really weird.
Personally I'd can see the self-secure and calm Jadeite as a heartbreaker easier then Nephrite, who is very solitary and sometimes a bit grumpy. And, considering the way he reacted to Naru, it is probably a safe bet that Nephrite haven't been in any more serious relationships. Might be those lies that drive the girls away...
Don't recognize the term? Well, it's a fan-made manga, sold for the production cost only. My current layout is based on a doujinshi (dj for short)
The only ones I've read featuring the first King also happen to be yaoi (homosexual content) but I don't know if this is a rule or exception. As you can see on the image above, Nephrite/Jadeite is the usual pair.
Some dj's are very beautifully drawn, but I dislike the way they always make Jadeite so weak and... how should I put this, virginal? Nephrite comes on to him (pretty strongly) and he's always so weepy! Not counting that we never ever, see any of those tendencies in the anime or manga, Beryl would never have made him a commander if he'd been so frail.
But, this doesn't mean anything, because in yaoi-land there's an universal rule which states that the tallest person is seme (the guy on top) and he's one cool bastard who'll practically force the uke (bottom guy) into bed whenever he damn well he feels like it. And guess who gets the uke part? Yeah, you got it.
Anyway, I still like doujinshi. They can be really funny, and it's always nice to see more of Jeddy. Plus, I'm a yaoi nut ;P
I just wish I knew Japanese, so I could understand what the heck they're talking about.
Disclaimer: Sailor Moon © of Naoko Takeuchi.