STD Immunity

"588. Paladins are immune to STDs, but if I take advantage of this ability, I lose it. Wonderful paradox, isn't it?"

—Things Mr. Welch Is No Longer Allowed to Do In An RPG

Any sort of porn, especially those that never seem to end, will be absolutely blind to things such as venereal diseases, possible pregnancy, and even bodily wastes in the orifices that are about to get plugged. In fact, everything is clean, pristine, and completely safe, no matter if it's between family members or if it's from some "dirty" prostitute pulled off the streets.

This, unfortunately, is a horrible, horrible example of Did Not Do the Research; actual porn studios have their "actors" go through rigorous STD testing, enema cleansing, and contraceptive use throughout their careers, and if any of them break those practices (especially with the STD one), they get blackballed really quick. (Though this has not always been the case, and 90s pornstars have gone on record as stating that herpes was an omnipresent occupational hazard.) It's easier to get away with in fiction, as it's, well...fiction, and the lack of proper protection or pre-sex cleanup can be Handwaved away, but even the "real" stuff can give the impression that there's no need to worry, and if Viewers are Morons and don't know a thing about the dangers of sexual intercourse, they could try it themselves and find out the hard way just how wrong that impression is.

Of course, many writers are aware of the risk of catching an STD but since the plot of the story is not about somebody dealing with an STD they avoid bringing it up no matter how much of a risk it should be. In porn, being a fantasy genre, this is an acceptable break from reality so long as people aren't actually taking life lessons from porn.

The whole "pro-condom"/"no-condom" thing comes up among porn purveyors and consumers a lot, and the funny thing is that many people who religiously use condoms in real life still admit that condoms turn them off in porn scenes—it ruins the whole "uninhibited fantasy" aspect of the thing. Given that "social conscience" and "porn" are almost by definition miles apart on the cultural radar and that porn basically only exists to fulfill fantasies, this is unlikely to change anytime soon.

In fiction as well, "good" people seem to be immune to STDs, while "bad" people catch them. Justified if being "good" means having had few or only one sexual partner; if the "good" people are as promiscuous as the "bad", not so much.

In Real Life, most sexually-transmitted diseases are hard to immunise against, so no true immunity has been achieved, vaccine or otherwise. For now, cutting the number of syphilis, gonorrhea and chlamydia infections through antibiotics and preventing HIV transmission by pre-exposure and post-exposure profilaxis, as well as having a condom on standby are about the best we can do when it comes to sexual safety. And, in case you're wondering why we haven't advanced that far, we did - HIV kills and sex with an HIV carrier meant certain death, so having medicine that actively prevents secretion of the virus during sex is a major breakthrough. Most agree condoms during sex are no fun, though, so all we can hope is STDs get eradicated sometime in the future by further medical advancements.

No real life examples, please; as we mentioned above, STD immunity hasn't been achieved yet.

Examples of STD Immunity include:

Comic Books

Top Ten, a Police Procedural in a city populated entirely by super people features a prostitute called "Immune Girl" who has this as her superpower. Sadly, she's not immune to the local Serial Killer who's been targetting the city's hookers.
During Chuck Austen's run on X-Men, there was a passing mention by Husk that mutants apparently can't get HIV. This was never mentioned before, was likely meant to include as a Hand Wave for why Archangel's healing blood didn't carry the really obvious health risk, and has never been mentioned again.
- Angel also mentions it and a doctor confirms it.
- One presumes that this applies to Wolverine (and by extension Daken and X-23) or any other character with a sufficiently strong healing factor.

Film

In I Love You Phillip Morris this is played straight when Steven dies of AIDS and Phillip, his lover, wonders why he wasn't affected (condoms are never mentioned). Subverted when it's shown that Steven was only faking his death and Phillip was never meant to find out. Though Steven's previous lover did actually die of the disease, so straight again, as Steven didn't catch the disease from him.
Two words: James Bond. No STD's, no known condom use, no accidental pregnancy. (Saturday Night Live once did a sketch revealing that Bond has an unspeakably large amount of STD's.)
- Your Logic May Vary: While the condom use is never shown on screen, neither is most of what happens in bed. So he might have used them.

Literature

There are at least some amateur erotica writers who note (partially in humor) either in footnotes or in their profiles that all their stories are set in a world where STDs are non-existent or have been cured completely.
- Likewise, in Harry Potter Fanfic characters will usually cast a "contraceptive spell" before getting down to business. STDs, however, are rarely - if ever - mentioned.
- In some Harry Potter fanfic, wizards simply can't catch normal Muggle diseases. They occasionally get bizarre magical ones, but that usually involves comical consequences like one's face being covered with feathers, and is fixable with potions or a trip to the hospital.
The women in Harlequin romance novels seem to be immune to STDs while being simultaneously extremely fertile; if any negative consequence of a sexual encounter arises, it will invariably be an unwanted pregnancy, which will always happen if attention is drawn to them having unprotected sex.
In Robert A. Heinlein's novel To Sail Beyond the Sunset the "good" protagonist never has a problem with STDs, despite a very healthy sex life. Her "bad" daughter, however, gets some. At least the "good" protagonist does actually use condoms, although only for birth control. When she is pregnant or willing to have children with someone during "spouse swapping", she skips the condom. Yet the STDs know to leave her alone, since she is "good".
- The difference between "a healthy sex life with people you trust" and "anything that moves" is apparently too vast to grasp.
  - Considering many people with STDs don't even know they have them (at least in the early stages), it doesn't matter how "trustworthy" your partner is, unless they have never had sex or been exposed to bodily fluids, unless they get tested, which won't reveal a recent infection and can have false negatives, as well.
Never fully explained in Jacqueline Carey's Kushiel's Legacy books, though the ability to avoid pregnancy is. It may just be a D'Angeline thing.
Averted in the Tom Clancy novel Without Remorse, where protagonist John Kelly contracts a venereal disease from the abused woman he rescues. The doctors cure him without revealing it after she is murdered.
Averted in All American Boy by William J. Mann where the main character visits a friend/mentor of his who is dying from AIDS. He also reveals that his previous lover caught the disease, while he's "clean" because they had an open relationship.
Painfully averted in Someone Elses War, a book about Child Soldiers trying to survive and escape their horrific lives.

Live-Action TV

Buffy the Vampire Slayer gives us at least one example, maybe two. Faith has been stated to have lots of casual sex with no hint of condom usage yet never gets pregnant or infected with anything. This might be because of her being a Slayer, though. Who knows what those powers do to STDs. Pregnancies are harder to explain, seeing as at least one Slayer had a child (Nikki Wood, the Slayer Spike killed in 1977 and stole his famous leather duster from, is the mother of Robin Wood, principal of the new Sunnydale High). Vampires are also likely immune.
Also repeatedly averted in the soft-core series Red Shoe Diaries. Characters would often bring out the condoms just before getting it on. The show may be about casual sex, but it's about casual safe sex.
Averted in the fifth season of Supernatural as Sam is shown contracting gonorrhea and herpes, though this may be due to Sam being "evil". Since Sam is also repeatedly shown swallowing total strangers' bodily fluids, this is yet another reason why one should avoid having sex with Sam Winchester.
Averted on Gossip Girl where man tramp Chuck Bass has contracted at least a few STDs in his day, and on one occasion bonds with his uncle over what medication they got for gonorrhea.
Averted in Veronica Mars. That's how she guesses who raped her.
In an episode of Stargate Atlantis, the doctor finds it very odd that the woman from a primitive village who they have invited back to the base (and have put under a med test) is completely healthy, including a lack of any STDs. Turns out she's actually an ascended Ancient taking human form, so she's kinda beyond that.
- An odd aversion in an episode of Stargate SG-1, where O'Neill has sex with a local woman, and is infected with nanites that cause him to age rapidly.
Played straight on ER, where hospital stud Doug Ross managed to have drunken one-night stands with numerous women, yet never caught anything. Averted with Jeannie Boulet, who caught HIV from her cheating husband and feared she had given it to her boyfriend (she hadn't).
Brutally averted during General Hospital's AIDS storyline, where Stone had AIDS and his girlfriend Robin eventually tested positive, despite two previously negative tests. Viewers pleaded for her to remain negative, but the writers felt that this would be irresponsible, as the two had had unprotected sex numerous times (they stopped using condoms once she began taking the pill) before they even knew of Stone's diagnosis.
In Sex and the City, Samantha has sex with a ludicrous number of people, and she only has one STD test in the entire series. (It was negative, of course.) Neither has she ever had a pregnancy scare.
- She did mention having had two abortions in the past, and makes references to regular condom use.
- Averted with Miranda, who had to deal with being diagnosed with chlamydia and then having to go through the process of calling all the men she'd ever slept with to inform them.
- Charlotte also once got crabs from having sex with a college student.
Let's not forget Two and A Half Men, where not only does Charlie not get STDs, but it's commonly pondered why.
- It is mentioned, at least a couple of times, that he uses condoms. One episode showed him buying several packages, of varying types.
Averted in Grey's Anatomy, when one episode features quite a few of the doctors having "the syph" from constantly hooking up with one another.
- To clarify, the first season finale was about the hospital dealing with a syphilis outbreak amongst the staff from everybody sleeping around. Also serves to reveal that one of the characters cheated on their partner.
Lampshaded but ultimately left ambiguous with regards to Barney in How I Met Your Mother, where other characters often imply that Barney must be crawling with diseases after the number of women he's slept with, but this is never confirmed in canon. In one episode, after a stunt at the Superbowl causes dozens of girls to call him up for a date, he proudly tells the gang that he's going to sleep with every girl who calls him, but has hired Ranjit as his chauffeur rather than take public transportation, because "Ew, germs!"
Similarly, Joey from Friends is often the butt of these sorts of jokes. For instance, Chandler notes that Joey's advice will be useful if it's about "pizza toppings or a burning sensation when you pee."
In Deep Love it's noted that Ayu, a prostitute, and all other noted prostitutes use condoms with their clients most, if not all, of the time. Averted eventually when Ayu does contract AIDS and dies from it. It's also stated that Yoshiyuki's father has the disease at the end.

Tabletop Games

In 3rd Edition of Dungeons and Dragons, paladins were immune to disease by divine blessings, but they tend not to be the type to sleep around. However, Sune, the Goddess of love in Faerun, also promotes paladins, and like other divinely empowered beings, they are expected to promote their goddess' interests.
Also the case in FATAL, which, despite its heavy emphasis on sexual activity and its claim to be "the most...realistic and historically/mythically accurate role-playing game available", never even mentions STDs.

Video Games

The universe of The Spellcasting Series is STD-free. The narrator takes care to mention that fact, as Ernie Eaglebeak tends to shag every woman he can get his hands on.
Literal example in The Witcher. A Witcher's mutations render them immune to disease and cause sterility. He makes good use of both.
Averted in Fable II, having unsafe sex can cause your character to get an STD. This is mostly played for laughs, though, as STDs don't actually do anything.
Averted in Wasteland where sleeping with a hooker will always give the character "wasteland herpes". This does affect the character's health, though it can be easily cured at any hospital. Also noteworthy in that this is one of only six diseased/poisoned status afflictions in the entire game.
Subverted in Dragon Age II, in which the absurdly promiscious Isabela apparantly gets STDs often, but she knows a long-suffering mage called Anders who can get rid of them with no real difficulty.
- One NPC even claims she's so promiscuous that there's an STD named after her. And...yes, she's a potential Love Interest for the main character.

Web Comics

Girls with Slingshots: Angel thinks you can only get an STD from contact between a penis and a vagina, which is convenient for her since she's apparently been banging every female who asks for the last ten years. Thea, a similarly-inclined woman who was similarly inclining Angel until recently and has caught restless leg syndrome, is understandably flabbergasted at Angel's delusion.

Web Original

Justified in Chakona Space, Chakats have genetically enhanced immune systems and well-defined estrus cycles. So despite their habitual Polyamory they never catch anything and rarely get pregnant by accident (as opposed to on purpose). And sometimes, on the rare occasion that a chakat is in heat and doesn't want kids, a brief mention of wearing protection is added.
The Kristen Archives, a (NSFW) collection of sex stories which dates back to the UseNet era, was prone to fictional tales which described various blatantly unsafe activities... followed by a disclaimer like "It's okay to *READ* stories about unprotected sex with others outside a monogamous relationship. But it isn't okay to *HAVE* unprotected sex with people other than a trusted partner. 4-million people around the world contract HIV every year. You only have one body per lifetime, so take good care of it!" at the very end.

Western Animation

Subverted by Quagmire of Family Guy, who is apparently the venereal equivalent of Mr. Burns in that he carries every STD known to man but shows no symptoms.

Quagmire: "Joke's on you, I already have [Hep C]!"
Peter: "Okay, what about... (stabs Quagmire with hypodermic needle) Gonorrhea!"
Quagmire: "Patient zero."