Among the less common of the planetouched, the changelings are those with a bit of Limbo in them; either descended from those beings that stand for chaos — most prominently of which are the tanar'ri, the eladrin, or rarely, the slaadi themselves — or affected by the transformative nature of the planes of Chaos while still in the womb. And as Chaos itself, a changeling is a fluid creature, able to transform itself and take on nearly any humanoid appearance they wish.
As with all planetouched, changelings have existed since the first mortal ventures onto the planes. However, they tend to be rare, even rarer than their diametric kin the zenythri; few are biological descendants for the slaadi are not in the habit of mating with mortals, while the tanar'ri and eladrin are so rarely expressive of chaos at a level more prominent than their "moral" nature. Those literally planetouched therefore make up the vast majority of the changelings. Due to their slim numbers, there have never been any recorded communities of changelings, and few major figures of their kind.
Changeling outlook can vary as much as their physical form, but in the extreme they tend to fall into one of two categories. The first are those free of identity, that see persona as nothing but a set of clothing, a mask that can be changed as easily as one changes a set of clothing. Such changelings rarely bother keeping in their natural form, trying out as many ways of life as they can. Integrating themselves into society in various roles to try them out before moving onto the next. They tend to have vast interests in all fields, but rarely enough passion in any one to truly pursue it long-term; very "jack-of-all trades", these sort. They tend to have a very Sensate- or Signer-esque outlook on life regardless of if they actually join either of those factions, and though they may make friends as any individual, those friends may find it difficult to keep up with who and what the changeling is at any one time. As such, they tend to be severely individualistic, rarely making strong connections with any one person.
The other extreme tends to keep to a single specific form or a set of forms with some common identifying trait (not necessarily their natural form), seeing their natural abilities not as a blessing or curse but merely a tool, a means to an end rather than an end in itself. They acknowledge the freedom their powers give, but they believe that constantly changing themselves will only hurt their connection to others, that if they dip into everything then they've truly felt nothing. While they may explore the potential their form gives them, they are honest about it with all, always careful to have some facet by which their friends and colleagues can tell who it is they're talking to.
In societies aware of them, changelings are often distrusted for their abilities, even more so than tieflings. The fact that a changeling can change their appearance at will often leads to suspicion similar to that given to doppelgangers, unintentionally ostracizing the changeling from others. As a result, many changelings will choose to hide their talents not for any personal philosophical reasons, but merely to better keep trust with those they keep relationships with.
Changelings, as all planetouched, are perfectly mortal despite their heritage. They do not hold their shifting abilities from birth, but rather around the age of maturity, and as such one cannot tell until this point whether the child is in fact a changeling or not. Once they reach that age — around the same age as the non-changeling parent, or 16 if both parents are changelings — they come into their own quite naturally, requiring little to no training before they reach their shapeshifting ability's full potential. On average a changeling will live one and a half times longer than its non-ancestral parent's species, or about 100 years for those descended from two changelings, but their lifespans can vary widely, with some known to range from three-quarters to three times the lifespan of their non-ancestral parent.
Changelings are born with a singular natural form derived, as with any mortal, from their parents; if one of their parents happens to be a changeling themselves, then it will be the form at conception that determines the child's traits, not necessarily their natural form.