The Asari are one of the most prominent of the alien species within Mass Effect, as well as being arguably the most respected and established members of the galaxy. This is due in part to their very long lifespans, roughly 1,000 years, which gives each Asari ample time to have a major effect on the galaxy, and also because the Asari were the first of Mass Effect's sentient races to achieve interstellar travel and find the Citadel since the extinction of the Protheans.
There are a number of story missions in the Mass Effect trilogy which deal directly with Asari persons and issues, from Shiala, whom Shepard meets on their quest for Saren, to the powerful ruler of Omega, Aria T'Loak. Each member of the Asari race provides different insights into the majestic species, perhaps none moreso than Shepard's close friend and crew member Liara T'Soni. As a whole, the Asari people are a species fixated on the quest for knowledge, working to understand everything they can about the universe, and their culture is entrenched in this goal - forming an intricate tribal society to support it.
Though regarded as the wisest and most advanced species of the Citadel races, the Asari did not achieve this feat on their own, despite their efforts to appear as if this was so. The Asari were, in fact, first discovered on their home world of Thessia by the Protheans when they were still in power long before the events of Mass Effect, and they created a guise of the goddess Athame to commune with the Asari and accelerate their development. After establishing the Athame Doctrine and placing a beacon on Thessia the Protheans left the Asari to develop. Though the Protheans would soon meet their demise by Mass Effect's Reapers, the Asari were spared in the purge and thus able to continue on their rapid evolution to becoming the advanced species of contemporary era.
Aspects of Asari Society In Mass Effect
Asari culture is an amalgamation of their quest for knowledge along with the religious structure put in place by the Protheans and their views on a society with open trade and information sharing. As one of Mass Effect's species that lives for a millennium they have a much longer view of things, and this is reflected in their pursuit of understanding. Given that they do live such long lives, they don't have the rushed need to establish themselves in a place of dominance, and will instead seek to gain whatever information they can from others. This manifests both in their relations with the Citadel races and within their own society, as there are no rigid systems of governance but rather a multitude of republics working together within the overarching Asari values of consensus.
With these values Asari seek balance above all things, which, along with their quest for understanding, is why they are such effective diplomats in the Citadel and the ones responsible for bringing many of the species into fold. After discovering and settling the Citadel they become a driving force in the Mass Effect universe, actively working to find other races capable of interstellar travel, establishing trade routes, and creating necessary guilds and alliances to foster growth within the galaxy - unbeknownst to them, in a similar fashion as their Prothean forbearers. As the first race to discover the Mass Relays, the Asari were uniquely positioned for this role and in accepting it became a cultural influence over the entire galaxy.
The Asari religion is pantheistic, with a belief that the everything in the universe is connected in one giant living consciousness. This is paired with the stages of the Asari lifespan, in which those in the final stage, known as Matriarchs, function as elders among the Asari people. Their beliefs were cemented as an effect of the unique mating process of Asari.
As a mono-gender species that isn't asexual, they reproduce through a process called "melding" in which they join consciousness with their partner, sharing memories, genetics, and more to create a new life with equal parts from each parent. As they discovered new races they learned they could meld with any of Mass Effect's sentient lifeforms, furthering their belief of a connected universe.
Though the offspring is still always Asari, they take equal on traits of both partners regardless of the parent's gender or species, which is why it's considered essential to meld with members of other species to make sure new experiences, traits, and knowledge are brought into the Asari race. By the time of the events in the Mass Effect series it is frowned upon for Asari to mate with other Asari as that doesn't bring anything new to the species.
Phases of Asari Life In Mass Effect
Asari lifespans are divided into three phases: Maiden, Matron, and Matriarch. The first few hundred years of an Asari's life is known as the Maiden phase, and it's in this time that Asari are driven to explore new things. As adept biotic users this is generally the time they may join their local military forces, take on work as mercenaries, begin a journey of scientific discovery, or perhaps even find work as a dancer at one of Mass Effect's many bars. However it manifests, this period is the time in which Asari find themselves in the world.
The Matron phase is when Asari desire to settled down for a time and raise a family. This period is usually somewhere in an Asari's three hundreds, but varies depending on their life experiences and can be triggered earlier, as shown in some of Mass Effect's characters. Given the nature of their culture and long lifespan Asari will, unless bonding with a Krogan or another Asari, outlive the other parent, but with their long view of time they work to make their time with their partner as meaningful as possible. For the next few hundred years of their live Asari will dedicate themselves to their family and raising their kids before they reach their Martiarch phase.
The Matriarch phase of an Asari's life usually comes in the last few hundreds years, after they've had time to adventure and explore and raise a family that is, by then, grown as well. It is at this phase that Asari will work as counselors and advisors within the Asari culture, providing the younger generations will valuable insight from their centuries of wisdom accumulated. Even in the Matriarch phase, though, as with the others, there are exceptions. Not all Asari in Mass Effect follow this traditional path.
Between their intricate culture and their status as one of the most advanced races in the galaxy, the Asari provide some of the most incredible pieces off Mass Effect's universe and storylines. From fan-favorite characters to direct tie-ins with the Protheans that came before the Contemporary Era, they supply Mass Effect some of its best content and characters. Far more than just sci-fi tropes, the Asari are an amazing science-fiction culture.