'''Basic Trope''': A tendency for most characters in a work to be only children, save for when their siblings are important to the plot. Has various implications and effects on the setting in general.
* '''Straight''': Out of all of [[TheHero Sol]]'s companions, the only ones with siblings are [[FailureKnight Ernst]] (with his deceased sister [[TooGoodForThisSinfulEarth Marie]]) and [[EverythingsBetterWithPrincesses Princess]] [[LadyOfWar Velvet]] (whose brother is the EvilPrince [[ThemeNaming Satin]]).
* '''Exaggerated''': This lack of siblings extends to most of the world; there are very few uncles or aunts, resulting in even fewer cousins or other extended family situations.
* '''Downplayed''': Only three significant characters are only children, while all the others are limited to one or two siblings of vastly different ages.
** They live in a CrapsackWorld where the population is closely monitored and most families can only have one child; only the higher class can break the law without facing severe punishments if caught.
** Sol is a only child (like many others) since sadly it is set in a time/world where the maternal death rate is ''so'' high that a women's first pregnancy is almost always a death sentence.
** Sol and his friends are part of a fantasy species where women only have one egg and are deemed infertile after their first child.
** Sol might actually be of had many sisters and brothers...Once. But this is a AfterTheEnd world, where the vast majority of people have died. If you're lucky enough to have survived, it's '''very''' unlikely that anyone else in your family would have too.
* '''Inverted''': Nearly everyone comes from massive farm families with at least eight siblings who only receive mention as part of a NoodleIncident involving Alice being mistaken as a boy. Jacob is the sole exception. It's revealed that this is because his father fell apart after his mother died.
** Many of the characters' parents conceive after it is established that they only have one child each.
** None of the main characters' siblings are mentioned at first, but they start appearing in later episodes.
* '''Double Subverted''': However, their new children are immediately killed.
* '''Parodied''': ???
* '''Zig Zagged''': ???
* '''Averted''': All the characters in a work have varying numbers of siblings, from more than eight to none, few of whom are important to the plot.
* '''Enforced''': LawOfConservationOfDetail keeps writers from creating siblings and family members that aren't important to the plot in some way, shape or fashion.
* '''Lampshaded''':"Hey guys, have you noticed barely anyone we know has any siblings?"
* '''Invoked''': ???
* '''Exploited''': ???
* '''Defied''': "What? Why should you just assume I was a only child? Realistically, you're more likely to have a sibling than not to have one. So there."
* '''Discussed''': "I've never seen someone call themselves a brother or a sister before. I'm not sure I'll live to, either. With the exception of the fair princess and her evil, estranged twin witch."
* '''Conversed''': "Isn't it weird how everyone's a only child in these books?"
* '''Deconstructed''': The lower reproduction rate means that parents have one shot at passing on their genes; one tragic death at the wrong time can completely wipe out that branch of the family line. While a prophecy states that a descendant of a former Hero will become TheChosenOne, the line is inadvertently snuffed out before the prophecy can come to pass. Hello, EndOfTheWorldAsWeKnowIt.
* '''Reconstructed''': But prophecies can't be broken that easily, as a single member of the family line has secretly survived by pure chance. They just have to find him.
* '''Plotted A Good Waste''': The lack of siblings turns out to be an important plot point, as it's an early sign that this world is not what it appears to be at first glance...
* '''Played For Laughs''': A RunningGag is that whenever a character asks their parents why they're an only child, the parents always respond with some variation of "You're ''more'' than enough for us, sweetie." (The character never seems to pick up on the subtext that this meant they were too much of a terror for their folks to risk bringing another similar kid into their world.)
* '''Played For Drama''':
** According to prophecy, only the descendants of the last band of heroes can defeat the emerging evil once and for all. Unfortunately, there aren't too many descendants left, and the current generation is made up of only children -- which TheEmpire is hunting down one by one...
** [[ChildMage Ichigo]] is initially forbidden from accompanying Sol because she's her family's only child. Prophecy requiring her presence be damned; they're ''not'' going to lose their baby...!
Back to OnlyChildSyndrome, and no, you don't have any siblings! There's only one Chosen One, after all.
%% Optional items, added after Conversed, at your discretion:
%%* '''Implied''': ???