Rachni Queen

Rachni Queens are the matriarchs of the hive-minded, insectoid rachni species. The largest of their species at about twenty feet long, queens are powerful and intelligent creatures who guide the soldiers and workers of their broods with a form of telepathic song, hinting that they also have biotic talent. This allows them to speak through 'receptive' beings, like asari commandos. Queens also carry the genetic memory of their mothers, effectively born with all the knowledge of the previous hive.

Queens resemble brood warriors but are much larger, with darker skin and glowing eyes. Though queens are usually mated to brood warriors, the reproductive processes of the rachni do not necessarily require a male counterpart. Queens carry the genetic information of their fathers inside them, allowing them to lay eggs even if no brood warriors are present. They are said to be able to lay an egg every few hours, resulting in an entire rachni colony within days.

Rachni queens live in nests deep underground, often on planets with harsh environments. This presented a problem for the Citadel Council during the Rachni Wars; the rachni combatants were only soldiers carrying out the orders of their queens, and at the time no Citadel race could survive on the hostile rachni homeworlds to negotiate with the queens. After failed attempts to halt the rachni advance, the krogan entered the fray, infiltrated the rachni nests, killed the queens on every homeworld, and hunted the rachni to total extinction.

Mass Effect
However, a rachni vessel had been left adrift with many eggs in cryogenic suspension. A corporation called Binary Helix found the vessel and brought an egg to the icy planet Noveria to hatch it, planning to clone the rachni inside to mass-produce an army, but instead they found a surviving rachni queen. She began to lay eggs, which Binary Helix removed from her presence to train the brood as obedient soldiers, only to discover that rachni must develop close to a queen to allow her mind to shape theirs and soothe them. Without the queen, the rachni went rogue and escaped, infiltrating and heavily damaging the facilities at Peak 15.

Matriarch Benezia, acting on orders of Saren Arterius, planned to use the rachni to destroy Saren's enemies, but Benezia needed more from this queen than her eggs. Using her biotics, Benezia took the co-ordinates for the Mu Relay from the rachni queen's mind, drawing on the rachni's genetic memory.

When Commander Shepard arrived and defeated Benezia, the queen saw the opportunity to appeal to Shepard for forgiveness, using one of Benezia's body to translate. The conversation gave the implication that the rachni queens were influenced by a 'sour yellow note', "a tone from space [that] hushed one voice after another", implying they were not fully responsible for the Rachni Wars. Wanting only to rebuild her species peacefully, the queen humbly asked what Shepard would do - kill her with the lab's acid tanks, or free her.

If freed, she escaped into the wilds of Noveria, remembering the kindness Shepard had shown and intending to pass those lessons on to her new offspring. The turian Council representative was concerned that the rachni could challenge the Citadel again in a few generations, but Shepard was able to argue that this queen was not like her ancestors. If Shepard killed the Rachni Queen by burning her with acid in the containment tank, the Council scolds Shepard for making the rachni extinct once more, with the turian representative asking whether humans take pleasure in the genocide of other races.

Mass Effect 2 Consequences

 * If the Rachni Queen is set free, A newscast reports sightings of scout ships consistent with rachni design, which would suggest the new rachni colony is spacefaring, if not building a full fleet.


 * If the Rachni Queen is set free, she will send a message through an asari, on the planet Illium, thanking Shepard for freeing her. She seems to be making good on her intent to pass on the kindness Shepard showed her, as the asari who relayed the message had her life saved by the Queen on a remote world.


 * The asari messenger in Mass Effect 2 explains that the Rachni Queen believes that her ancestors were put to war against their will as "the rachni are not a naturally aggressive species". The asari explains that when something "soured their singing" it could be translated as mind control. Shepard can ask if this is Reaper indoctrination but the asari seems uncertain, though the symptoms match and the Rachni Wars proved the rachni could be powerful allies for the Reapers. However, in gratitude for the Commander's actions, the Rachni Queen instead promises her aid to Shepard "against the coming darkness".

Trivia
According to The Art of Mass Effect, the design of the rachni queen was influenced by the appearance of beetles and insects. This book, in addition, gives the length of the queen as fifty feet long.