Sex Position

A character's preferred sex position during sex can often be a point of contention and discussion among shippers. 
==Top and Bottom==
Personality attributes displayed in canon (or fanon) are often used to determine whether the character is a top or a bottom in sexually explicit fanworks; conversely, some fan creators intentionally subvert expectations when assigning these roles. 
Some fans exclusively read or write certain characters as tops or bottoms in fanfiction.
The terms top and bottom are also used for cis femslash ships despite the fact that both parties can simultaneously penetrate each other via fingering. In this case, top/bottom more refers to dominance/submission, or assertion/vulnerability.
Top and bottom are sexual slang terms and do not originate in fandom.
===Top===
Top, often synonymous with seme, is someone in a sexual encounter who penetrates, asserts, and/or is the Dom in a D/s relationship. They may be simultaneous, although not inherently - dominant partners may be penetrated while submissive partners may do the penetrating. Either way, top generally refers to the "taker" in a sexual relationship, the one who exerts more power and control over the other. 
Among slash fans, tops who penetrate are usually the taller, or older, or more emotionally controlling character. If any contradict, fans tend to prioritize physical attributes over personality traits. 
Penetrating tops can occasionally also be depicted as the more generous character in a pairing - as long as they are taller/bigger - while the bottom relinquishes their emotional control to the top during sex.
In gay sexual slang, the top is also referred to as the "pitcher."
===Bottom===
Bottom, often synonymous with uke, is someone in a sexual encounter who is being penetrated, makes themselves vulnerable, and/or is the sub in a D/s relationship. As with tops, being penetrated and being submissive are not inherent of each other. The bottom is usually the "giver" in a sexual relationship, although in many ships this can be one end of a character being completely submissive, or the other end in being bossy and controlling a la power bottom. This tends to be as long as the bottom is smaller/shorter - though again, some fans do like to subvert these ideas.
Bottoms in pairings with male characters are frequently seen as the more feminine of a pairing, whether in aesthetic/fashion, personality, or simply by bone structure and body type. Male characters who are bottoms in slash pairings are commonly described as "lithe" and "thin," and sometimes "smoother" than their sexual partner.
In fanfiction, bottoms tend to take on the more extreme personalities during sex, either being desperately submissive, or pushy and slutty. Or both.
A synonym for bottom in gay sexual slang is "catcher."
===Switching/Versatility===
Some fans headcanon their ships as being versatile/switching, either simply because they do, and/or to disparage binary ideas of couples exclusively topping/bottoming during sex. In fanworks, this is usually portrayed with characters in multiple sexual situations, with each character getting a chance to be in each position at least once. Sometimes - though rarely - characters may even discuss who is topping/bottoming prior to the sex (penetrative, oral, etc.)
===Ship Names===
In (definitely Chinese, Japanese, and Korean, but other languages as well??) top/bottom preferences are widely distinguished by the name-order in the shipname, the top being named first. For exmaple, in SasuNaru vs. NaruSasu "SasuNaru" is the ship name for portraying Sasuke as seme, whereas "NaruSasu" is the ship name for portraying Naruto as seme. How widespread this convention is varies a lot by fandom in English language fan spaces. In newer fandoms such as Genshin Impact it's so widespread that it's considered common courtesy to tag your ship according to dynamic,Explained in the List of Genshin Impact Relationship Names. Or for an example, that warns users #do NOT tag this as “Zho//ng//Chi” or “Zho//ng//ChiLi”#only use “TartaLi” when tagging our Tartaglia x Zhongli work -- meaning that the original poster only wants people to interact with/interpret their work with a top!Tartaglia and bottom!Zhongli dynamic. but in older fandoms such as Naruto many Anglophone fans may be unaware of the difference and use NaruSasu and SasuNaru interchangeably.
Older and more Anglophone/Western fandoms might be more likely to use bang descriptors such as Top!Joe. Portmanteau names with the characteristic in question also get coined, for example Toplock.
===Top and Bottom: Other Commentary===
===Top and Bottom: Further Reading & Meta===
* , by flambeau (2003)
*"Why do you think Lexa is a bottom?" by lingeringlilies on Tumblr, about Clexa (2016) (Accessed 1 October 2017)
*"Who tops more, Draco or Harry?" by snowgall on LiveJournal, about Drarry (18 March 2015) (Accessed 1 October 2017)
**HD-fanfair analysis (6 April 2015) (Accessed 1 October 2017)
**HD-smoochfest analysis" (18 May 2015) (Accessed 1 October 2017)
*"angel anal" by missyjack on LiveJournal, about Castiel (7 March 2010) (Accessed 1 October 2017)
*"TOPLOCK VS. BOTTOMLOCK: OH DEAR GOD WHY? HOW??" by chucksauce on Tumblr, about Johnlock (6 August 2014) (Accessed 1 October 2017)
*Top/Bottom on the Supernatural Wiki (Accessed 1 October 2017)
*Top!Joe, a controversial trope in The Old Guard fandom due to the perceived racist implications of portraying a POC as a domineering sexual partner.
==Penetrative Sex==
Penetrative sex is sex involving the penetration of a body part or an object into the orifice of another's. It is generally associated with a penis, being inserted into either the vagina or the anus of another. It can also include sex toys doing the penetrating, like pegging, or the mouth being penetrated, but in fandom is rarely considered as such.
===In Slash Fandom===
Cisgender M/M slash penetrative sex is common point of fixation for DFAB (designated female at birth) writers and readers, as it can lend DFAB fans to be able to be in the position of penetrating within the story. It also puts cis-male characters in the position of being penetrated, which DFAB women are often not able to experience.
Some take issue with the way penetrative sex is portrayed in slash fandom, however. Many are critical of placing them in stereotypical heteronormative roles, with the penetrator taking the position of dominance/masculinity/man, and the penetrated being depicted as more submissive/feminine/womanly. Fanworks are also prone to using penetrative sex as a way for the top to assert control over the bottom, which may be appealing to some readers, but also may be problematic in enforcing emotional or personality stereotypes to sex positions. 
Additionally, penetrative sex is considered by many to be "real sex" or the be-all, end-all of sex. Especially with barebacking, which is relatively common, this may be because penetrative sex can be seen as "claiming" or "ownership" between both characters. Though not frequently discussed, this is still an issue among some fans, as it enforces the idea of "real sex" being penis-centric, if not forcing both parties into a fixed position of "top"/"bottom" and their connotations. Many - real people, and thus fictional characters alike - may even not desire or enjoy penetrative sex at all. Oral Sex, frottage, and handjobs are also valid forms of sex, despite not always being considered as such, and are often featured in slash stories as sexual encounters that are not as meaningful as penetrative sex, which then comes more towards the end. More often than not, penetrative sex is the resolution of UST, as opposed to any other form of sex.
Because of top/bottom attributions, many within slash fandom prefer interpreting their ships as being versatile instead. 
Another issue with the concept of power being asserted via penetration also contributes to normalizing ideas of rape being perpetrated by a penetrator, when it can exist in multiple forms. 
===In Femslash Fandom===
In cis femslash works, fingering is common, though usually not referred to as "penetration." Sex toys may also be used, but not as regularly as fingering, cunnilingus, and scissoring.
=== Penetrative Sex: Further Reading & Meta===
*"Okay, fandom question here!" by lunabee34 on LiveJournal (5 April 2005) (Accessed 30 September 2017)
*"My first ever slash manifesto. (Also titled: A Comment Gone Horribly Awry" by starstealingirl at slashphilosophy on LiveJournal (25 May 2005) (Accessed 30 September 2017)
*"Meta: Sometimes I feel like a tool of phallocentric hetero-male-supremacy, and sometimes I don't." by lefaym on LiveJournal (20 February 2009) (Accessed 30 September 2017)
*"Meta-Fandom discussion: Heteronormativity and "activism" in shipping" by hells-half-acre on LiveJournal (14 June 2014) (Accessed 30 September 2017)
*"Workshop: M/F dynamics in M/M fic: wrongly applied gender roles and how to avoid them" by benitle at spnroundtable on LiveJournal (27 May 2009) (Accessed 30 September 2017)
*"Disjointed ramblings on the writing of same-sex pairings in fanfic, yeah, it's late, I'm too tired..." b rahirah on LiveJournal (5 February 2012) (Accessed 30 September 2017)
==References==
Category:Discussion
Category:Glossary
Category:Sexual Tropes & Kinks