This is a topic about culture among elementals. It needs some tweaking, so any input would be appreciated. This combines much of the info found in both 2E and 3x.
DIET
Elementals do not need to eat to survive, but must in order to grow. Elementals do not eat per say, so much as absorb sustenance. Elementals derive sustenance from elemental material or 'fuel' (e.g. fire elementals consume combustibles). Paraelementals derive sustenance by converting their opposite into their paraelement (e.g. ice paraelementals convert heat to cold). Negative quasielementals derive sustenance by consuming their opposite as well-- ash quasielementals absorb energy, dust quasielementals dissolve matter, salt quasielementals absorb moisture, and vacuum elementals consume matter and energy.
Some elementals, including archomentals, derive sustenance by absorbing the vital energy contained in flesh. Elementals who derive sustenance in this way generally appear as though they are ingesting flesh like most animals or outsiders would, but they are in fact absorbing it.
MARRIAGE AND BIRTH
This is a confusing issue to write for. We know that elementals aren't normally born sexually or via division, but rather when elemental material spontaneously acquires sentience (usually in areas of intense energy or matter), beginning their lives as elementites; tiny, insect-size elementals. To maximize their learning ability and chances for survival, elementites travel in swarms until they reach small size. Very few elementites survive long enough to reach such a size, and it takes centuries for them to reach it.
However, the Manual of the Planes introduced half-elementals, suggesting that elementals (and not just archomentals which are a bit of a different case) can not only reproduce sexually, but can reproduce with organic creatures as well. I cannot fathom how the latter would be possible.
At any rate, it doesn't appear as though neutrally and evil-aligned elementals possess strong parental instincts, since there is no indication in any official materials that elementite swarms are protected or reared by older elementals.
This would likely be different for good-aligned elementals.
For the time being, I am unsure how to categorize or describe their parental instincts. If regular elementals can reproduce sexually, then logically they would possess parental instincts. If not, then it would be illogical for them to possess such. Parental instincts not only cover the drive to protect one's children or children in general, but are also responsible for our drive to protect the weak and vulnerable. Thus, the answer to this question would determine a major facet of elemental personality and drive.
Would elementals who were born from the same rock or whirlwind possess a familial bond with one another? Who knows. The logical answer would be "no". The familial bonds between humans and other animals exist purely as a means of passing one's genes on. That is to say, we protect family because even if we were to die without passing on our genetics, out family (esp. immediate family) possess very similar genetic material, and thus can pass our genes on that way. Helping to rear the children of close family members also furthers this goal. However, whirlwind brothers and sisters are probably more likely than random air elementals to form a social group/tribe. The encounter data for elementals certainly supports the idea that they a social species.
It's likely however that good-aligned elementals will possess a drive to protect all living things, especially sentience.
To this end, I came up with the idea of Elemental Shepherds. Elemental shepherds are servants of the good archomentals. They are similar to druids on the prime and outer planes, and their purpose is to protect wells of elemental matter or energy which are likely to become sentient. Other elemental sheperds are given the task of rearing elementite swarms, educating (or training in the case of swarm members who will become elemental animals) and protecting them at least until they reach an age and size in which they can break off from the swarm.
RELATIONSHIPS WITH OTHER CREATURES
Most elementals seem to be rather xenophobic, and will outright attack non-natives they encounter on their home plane.
As I recall, there was something in some 2E material stating that elementals despise conjurers, who force them to do their bidding. Bringing an object or device with an elemental trapped inside to an elemental, paraelemental, or quasielemental plane is also likely to be a very bad idea.
Bringing a weapon or device enchanted with the element opposite of the plane is an even worse idea; this would be akin to bringing a sacred weapon to the Lower Planes, or a profane weapon to the Upper Planes.
Many are likely to suffer from some degree of superiority complex with regard to creatures of flesh. This could manifest as anything from pity to outright condescention. After all, organic creatures tend to possess delicate bodies that are easily damaged, and easily die if damaged in the wrong places. They must eat constantly in order to thrive, and require clean air to survive. Prime creatures in particular, require very specific environmental conditions (temperature, moisture, etc.) in order to survive. Because they possess a central nervous system, they must go dormant for several hours during a 24 hour period, leaving them vulnerable. Finally, with the exception of outsider species, they have finite lifespans.
Now, relationships with genies, that will be an interesting subject. Before I tackle this, I will have to read all of the official Al Qadim materials (esp. secrets of the lamp) If I remember correctly, it's pretty well established that genies hold sway over elementals of the same element. The question is whether or not this is entirely consentual. If not, then the relationships between genies and elementals are likely to be very, very strained.
RELATIONSHIPS WITH EACH OTHER
This varies by individual. Some are loners, but, if we were to use logic, most would congregate into small social groups, as this would be most conductive to survival. Neutral and evil elementals are likely to be indifferent towards elementals of different groups, even if they are of the same species.
>>can not only reproduce sexually, but can reproduce with organic creatures as well. I cannot fathom how the latter would be possible <<
It is possible that the largest percentage of such impregnations occur accidentally. Perhaps the ingestion of water, inhilation of heavy air, or other consumption of an element on its home plane brings with it a percentage chance of becoming impregnated with an elemental seed.
Other instances might occur when elementals near sentient outposts on their plane provoke the elementals to adopt humanistic (or appropriate) shapes and behaviors enticing some sentients to project non-existent emotions and attractions upon the entities, enticing them - as one might a high functioning animal - to engage in sexual affairs.
Then, druidic sorts and those with particular attraction to elements may, through their devotion, draw elemental forces to - and into - them during religious ceremonies.
Further possibilities exist - more than I have space to list here.
>>it doesn't appear as though neutrally and evil-aligned elementals possess strong parental instincts, …. This would likely be different for good-aligned elementals.<<
I’ll have to disagree here, I can see no reason why good elementals should be more prone to possessing parental instinct than evil or neutral. Among humans the family bond is designed for mutual protection, as well as - socially - maintaining control over real properties … as you don’t want some random person coming by and taking what you have worked hard to create. I don’t see that an alien intelligence, like that of the elemental, would develop in such a way - indeed I feel it would be doing the race an injustice just to make them “people made out of stone and fire”.
If anything I would be more prone to basing their dynamics off of insects - which elementals whom originated from the same Bonefire, Tornado, Whirlpool, Mountain, etc. possessing an innate connection to one another and - perhaps - treating that progenitive device as the center of their colony - both home and parent.
>>That is to say, we protect family because even if we were to die without passing on our genetics, out family (esp. immediate family) possess very similar genetic material, and thus can pass our genes on that way.<<
On the other side of that, there might be some sense of origin and desire to continue “spreading the flame” that first created them …. You might even have ancient elemental “bloodlines” which have maintained the heat of the same fire, drift of the same pool, etc. throughout the milenia.
>>It's likely however that good-aligned elementals will possess a drive to protect all living things, especially sentience.<<
I’ll have to disagree here as well - why would good aligned elementals be compelled to protect all living creatures when even good aligned humans don’t do so? I should expect that perhaps good aligned elementals are a bit more tolerant of organics than evil or neutral elementals, but for the most part their personalities should be unfathomable to humans - it would be like trying to put a personality to rain, or a forest.