One of the more fascinating Star Trek: Discovery characters is Saru (Doug Jones), the Kelpian First Officer of the U.S.S. Discovery. The most prominent alien on Discovery, Saru has mostly taken a back seat throughout the series while most of the action has revolved around Michael Burnham (Sonequa Martin-Green) and Captain Gabriel Lorca (Jason Isaacs). When Lorca was captured by the Klingons in the fifth episode 'Choose Your Pain', Saru got a chance to shine as acting captain. This week's episode 'Si Vis Pacem, Para Bellum' (translated from the Latin: If you want peace, prepare for war) showed a different and darker side of Saru.
While the Discovery was attempting an ultimately doomed rescue mission of the Starship Gagarin, which was ambushed by cloaked Klingon ships, Saru was leading an away team consisting of himself, Burnham and Lieutenant Ash Tyler (Shazad Latif) to the planet Pahvo. The proliferation of Klingon ships now equipped with cloaking technology taken from the Klingon Sarcophagus ship has been decimating Starfleet and is starting to turn the tide of the war against the Federation. Because of the imminent need to neutralize the Klingons' cloaking advantage, Discovery's secret away mission to Pahvo became Starfleet's highest priority.
Pahvo became strategically important to the war because everything on Pahvo -rocks, trees, even grass - vibrates with its own specific tone and is broadcast into space by a huge crystal spire that acts as a kind of transmitter. It's a planet of constant sound that emits a kind of music. Starfleet's plan is to harness Pahvo's electromagnetic frequency and use it as a way to create a sonar that can detect cloaked Klingon ships.
For Saru, however, being on Pahvo was torture. The constant sound and vibrations are more disturbing to his highly acute Kelpian senses. Pahvo was believed to be uninhabited but the planet has sentient beings that take the form of a blue cloud, though it doesn't register as a life-form to Burnham's tricorder. The beings on Pahvo are like harmonic clouds and exist to create harmony. Saru made first contact with the cloud and established communications with it. Later that night, Saru was awakened by the unceasing noise and wandered into the forest, where the Pahvo cloud entered him, read his mind and seemingly possessed him.
The next morning, Saru was calmer and happier than he had been, but he began raving about about staying on Pahvo and not completing their mission to attach Starfleet tech to the crystal transmitter and contact the Discovery. When he asked for Burnham and Tyler's communicators, he smashed them so they in turn couldn't reach Captain Lorca. Saru's peaceful and harmonic facade was soon shattered when he realized Burnham had disappeared and was on her way to the crystal spire to complete their mission.
Saru raced after Burnham and attacked her. As they fought, with Saru unleashing his pent up aggression towards Burnham from their tragic days on the U.S.S. Shenzhou, the Pahvo cloud brought Tyler to the scene. Saru begged forgiveness from the cloud for bringing their war with the Klingons to their planet while Burnham asked the cloud for their assistance to help them end the war. Burnham eventually attached her device to the spire, allowing her to contact and be beamed back aboard the Discovery.
As for what happened to Saru and why he went crazy and attacked Burnham to prevent her from contacting Discovery, when the Pahvo cloud merged with Saru, it read his mind and learned all of his fears. As a Kelpian, a race born to be eaten by his planet's predators, Saru exists in a constant state of fear. As he tells it, for his entire life, he has never known a moment without fear. The Pahvo, wishing to give him harmony, suppressed his constant state of fear and gave him emotional calm and balance, which made him want to stay on Pahvo forever. This was shattered by Burnham trying to complete their mission, which released all of his anger and resentment towards Burnham for everything she cost him from their service on the Shenzhou.
Related: Is Stamets From The Mirror Universe?
It's interesting to note the dual tales of Discovery officers undergoing personality changes. While Saru was finding harmony on Pahvo, on board the Discovery, the constant exposure to the Mycelial spore network has reverted Lieutenant Paul Stamets' (Anthony Rapp) personality from affable and relaxed back to being, in the words of Cadet Tilly (Mary Wiseman), his old "persnickety, grumpy self." Stamets has also been experiencing memory loss, not always realizing who he is speaking to or where he is. It's possible the harmonic beings on Pahvo might play a role in determining what's wrong with Stamets, stabilizing his personality, and perhaps revealing the truth about fans' Mirror Universe theory.
The beings on Pahvo are not unlike other beings that have been encountered in Star Trek like the Organians in The Original Series, who were evolved beings with god-like powers that actually stopped an impending war between the Klingons and Starfleet, or the Metron, another god-like being that used its power to settle a conflict between Starfleet and the Gorn. In this case, the Pahvo, which had been seeking to make contact with other species and make themselves known in the galaxy, used the technology Burnham brought them to make contact with the Klingons.
The Pahvo sent an invitation to Kol (Kenneth Mitchell), the new Klingon leader, to come to Pahvo, where the U.S.S. Discovery is in orbit. The Pahvo seemingly want to resolve this conflict and (perhaps naively) bring harmony to the Klingons and the Federation. Kol in turn wasted no time bringing the Klingon Sarcophagus ship to Pahvo. This sets the stage for a huge showdown in next week's mid-season finale of Star Trek: Discovery.
The mid-season finale of Star Trek: Discovery streams Sunday, November 12th @ 8:30pm ET on CBS All-Access, on Space in Canada, and internationally on Netflix.