
"To die will be an awfully big adventure."
Throughout "Naruto", there are seemingly countless characters that are obsessed with death (preventing it, bringing it and/or benefiting from it) and life (prolonging it). But, Hidan is not only the character farthest from truly dying, he is also the only one who is comfortable with the idea, desirous of it, even.
At one point, he even says (referring to the Leaf shinobi), "If they can kill me, I couldn't be happier."
...?
As I already mentioned, I believe that Hidan is not an old immortal, but one newly vested in his powers. Therefore, I don't believe that this confession (made in all seriousness) was due to the fatigue of long, lonely years. To me, the attraction stems from Jashin and the god's own love of carnage.
Hidan once said that his dogma didn't allow him to leave anything half-dead, complete and utter destruction is what is called for. And, in some disturbing way, it makes total sense to me that Hidan's love for his god would lead him to desiring that the ultimate of sacrifices to Jashin would become possible: his own death.
I mean, he's practicing it on a daily basis, what with the thirty minutes of "stabby stab, bleed on the symbol" that he does after every kill. It seems reasonable that he'd want to complete the action in an ultimate show of devotion. Because, despite hating the minor rituals (i.e. unnecessary injury, pain, or violence), Hidan does love his god and the truest of his religion's precepts: death.
We can see the difference between his views on pain/torture as opposed to outright killing in his reactions:
He tells Kakuzu that he thinks the rituals are a bother after the man complains, he yells loudly about his head getting cut off and the annoying pain of it all, he threatens to torture Asuma after he's injured but never comes through with the threat, etc.
But, when he does make the kill and the death washes over him, almost touching him but not able to mar his strange form of innocence, Hidan becomes closer to his god. And, although he has shown hatred for pain on his own part, he seems to relish the death pangs of others. Tasting the one thing he can never have.
This takes an ironic twist when Hidan warns Kakuzu that hell awaits those who are ignorant of the pain of others. And, one begins to realize that despite being a killer, Hidan's enjoyment and appreciation of death makes the kill more meaningful, in a way. He is a man who truly understands what the victim is feeling, as he touches the thin veil between him and his god.
This is, arguably, my favorite thing about the character of Hidan.
Another is linked to it and, in my opinion, it is the motivation behind every single choice that Hidan makes.

"Never is an awfully long time."
One thing that had always troubled me about Hidan was trying to figure out the answer to the big question: Why the hell is Hidan in the Akatsuki?
He doesn't seem to care about power or money or prestige or anything besides his beliefs, really. So, why, oh why is he collecting jinchurrikis and carrying on with tentacled old men?
Then, of course, I made my assumptions about his desire for death, and it made sense that being in the Akatsuki would not only insure massive opportunity for sacrifices to his god but also the slim chance that he might find himself in fatal circumstances, as well. But, more important than this, the revelation led to my second favorite thing about Hidan, and it was the realization that he is even more like the stereotypical "good" guys, in that...
He has a precious person, too.
Spoiler: Manga Evidence
If that isn't adorable, then I don't know what is!
For me, Hidan can have other relationships and dreams, but, when you get right down to it, Jashin is all that really matters to him. His immortality, money, time spent in prayer, vengeance, power...none of them mean anything to him. The only thing that he has ever shown real devotion to is Jashin (despite some obvious mild affection for Kakuzu).
Not only does that makes me all warm and fuzzy inside, but it also confirms my love for Hidan as a bad guy. For the less evil he gets, the more interesting and contrasting he becomes to me.
In addition, Jashin directly contributes not only to the creation of Hidan's affectionate side, but also to the maintaining of his purity. Much like Haku and Kimmimaro who fought and killed for their respective precious people, Hidan does the same thing. And, just like those two relative innocents, Hidan's kills seem to take little affect on his oddly pure (as explained in the beginning) heart and persona.
Gotta love that Jashin-sama!
But, as I said, while Jashin might be the most important thing in Hidan's unlife, he isn't the only thing...

"Two is the beginning of the end."
Without doubt or hesitation, I can say that Kakuzu and Hidan are my favorite partners in the Akatsuki. Not only are their interactions filled with vaudevillian humor and tongue-in-cheek silliness, but there is also a familiarity, a strange comfortableness that the pair has with one another which serves to make me smile. Also, their fighting abilities when paired, synch remarkably well. So, much so that some of the Leaf nin even commented on their extreme level of communication during battle. This comfort seems reflected in their ease with one another, a sibling/loverlike bickering being the norm.
But, most of all and perhaps oddest of all considering their organization, this pair seems to be the one that trusts in each other's abilities more than any other. They are confident that, in the end, when the smoke has cleared, the objective will be accomplished, the money collected, and the prayers said. Not to mention the fact that, as far as we know, these two are the only ones who chose each other: Hidan told Kakuzu that there was money in religion, while Kakuzu is the ultimate seamstress(...seamster?) and can sew up Hidan's wounds as they inevitably occur.
Plus, "Zombie Twins" does have a certain ring to it.
Spoiler: Some Manga Excerpts Showing Why I Love This Duo
The difference between him and the other boys at such a time was that they knew it was make-believe; while to him make-believe and true were exactly the same thing."
The last thing that I want to rave on about Hidan is something I have been pointing out this whole LAP, and that is his strange split (like so many of the Akatsuki) between good guy and bad guy. Often his traits placing him more firmly in the right than the wrong, as far as I can tell (and nakagos bunny said it well enough for me not to need to add anything).
And, this strange split also occurs in his function as a character. Yes, he's a bad guy, covered in black hoodoo, hexing the good guys into oblivion. Yet, he's comic relief.
Yes, he's a silly man raving on about this or that, making funny faces and being antagonized by Kakuzu. But, he also breaks past the tension of scenes that might otherwise be too painful to deal with. From what happens with Asuma and Team Ten to the clips of Kurenai, Hidan's outrageous humor and naivete keep things from getting too intense.
To end (finally), some people may think that Hidan doesn't have any development, that he's one-dimensional and an idiot.
But, you know, as Hidan would so eloquently put it, "Fuck those people!"
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First off, sorry that was so long and rambly. And, congratulations to those who made it through the whole thing!
All quotes were taken from J. M. Barrie's Peter Pan...just so you know ;P.
Second, Hidan Fanfiction...
To be honest, I found nothing that I enjoyed. It was all crappy pairing fics or poorly written, supposedly introspective oneshots. If anyone has ANY suggestions, PM me or post them, please. I'd really appreciate it.
Hidan Fanart: Actually used up my ten images, so here is a link to the Hidan_Fanart album, courtesy of the Hidan FC. All of the pictures that I have that aren't in here, I already posted.
http://s143.photobucket.com/albums/r133/Hidan_Fanart/?start=all