Spoiler Alert: Content covers the Thousand-Year Blood War Arc not yet released as AnimeBleach fans all know all about Uryu Ishida, the Last Quincy, but his Clan has expanded since the Anime as more characters are added to the mix. The Quincy are powerful human warriors capable of manipulating reishi to power their Spirit Weapons as they battle against Hollows to rid the world of evil.
Bleach fans do not see much of the Quincy Clan, with Uryu and his family known to be one of the few survivors. Although the Shinigami are wary of Ichigo's companion, Uryu is welcomed into the fight against Aizen, albeit reluctantly. However, the existence of the Quincy Clan becomes a crucial element to the survival of the Universe as their corrupt leader, Yhwach, makes a significant power play, all efforts leading up to the final battle in the Thousand-Year Blood War Arc.
The Collapse of the Worlds
Quincy, or Kuinshī in Japanese, literally means "Monk of Destruction" - a fine description for these fearsome warriors. The Quincy are humans who can identify and destroy Hollows much like the Shinigami, although they are widely considered to be polar opposites - in this case, the phrase "an enemy of my enemy is my friend" does not apply. For centuries the Soul Reapers have been very cautious of the Quincy Clan, believing that they will be responsible for the Collapse of the Worlds, causing chaos for the afterlife.
The Shinigami understand that there needs to be a balance of energy between the realms - equal parts of living souls, departed spirits, and Hollows. However, because the Quincy are so efficient at destroying Hollows, this equilibrium became unstable to the point where it could affect the survival of the Universe. If the Hollows ceased to exist, the human realm would become too heavy with living souls, and Seireitei would literally tip over, breaking the divide between life and death, causing utter chaos in the process. As far as the Gotei 13 are concerned, something needed to be done.
Wandenreich
Over a thousand years ago, as far as anyone could tell, the Quincy Clan were eliminated from existence when the Shinigami launched their assault. Unbeknown to the Soul Reapers, a small group manage to escape the attack and hid in the one place they would not be guarded at the time - Seireitei.
Using their powers of reishi manipulation, the remaining Quincy formed an "Invisible Empire" known as Wandenreich. The Quincy licked their wounds and built up their strength, waiting for the right moment to seek their revenge, and Aizen offered up the opportunity on a platter. While the Shinigami were fighting amongst themselves, the Wandenreich residents quietly conquered Hueco Mundo, abducted Tier Haribel, and formed an army of Arancar, in preparation for the Quincy Blood War.
Uryu Ishida
As the first Quincy that fans meet, Uryu Ishida raises suspicions as the only one of his kind seen by the Shinigami in over a thousand years, fighting alongside Ichigo no less! This youngster grew up in Karakura Town with his father, Ryūken Ishida, and grandfather Sōken, who all stemmed from the Gemischt Quincy Clan. Uryu learned all his sword and reishi skills from his grandfather, as Ryūken renounced the traditions of his people.
Upon discovering that Yhwach was responsible for his mother's death, Uryu joined the ranks as a Schutzstaffel in Wandenreich, earning the "A - Antithesis" ranking - the same grade as Yhwach himself. Much to the disdain of his fellow Quincy soldiers, the newcomer also claimed the title of Prince, making him the successor to the throne. Much to everyone's surprise, Uryu continues to fight alongside Yhwach when his friends arrive at the scene, attacking Yoruichi Shihoin and Ichigo with seemingly no regard. However, the young warrior changes targets to fight against Haschwalth, urging his friends to flee the scene, as he plans to destroy Wandenreich entirely.
Jugram Haschwalth
After the Anime, Jugram Haschwalth becomes Yhwach's right-hand man and the leader of the Sternritter, and this "B - The Balance" ranking Quincy soldier is a formidable force - powerful enough to break Ichigo's sword, Tensa Zangetsu. In a declaration of loyalty, Haschwalth willingly drank the blood of Yhwach, intending to absorb a fragment of his King's soul (and some of his power) in the process.
As Yhwach's most devoted disciple, the Sternritter Grandmaster feels threatened when Uryu joins Wandenreich and claims his title as Prince, knocking Haschwalth off his pedestal in the process. Another blow to his ego is the fact that Jugram is an anomaly, being one of only a very few Quincies born without the ability to manipulate reishi. As a young boy, however, he dedicated all his energy into perfecting his swords skills and was finally promoted into a position of power by Yhwach himself.
King Yhwach
As the main antagonist of the Thousand-Year Blood War Arc, this self-proclaimed "lover of peace" sure causes a lot of chaos! The Son of the Soul King and the Father of the Quincy sees no value in honor, justice, or blind loyalty, and Yhwach therefore leads his troops with a difference - forcefully recruiting them into his service while in the same breath referring to his subordinates as sons, often fondly so. He possesses the ability to absorb the powers from other beings with the use of his Auswählen, giving him a distinctive God complex. His goal is to combine the realms of Humanity, Seireitei, and Hueco Mundo, defeating his father, the Soul King, in the process. As much affection as he seems to hold for his Quincy soldiers, Yhwach easily sacrifices their lives for his cause - even absorbing the powers of his most respected leaders, Gerard Valkyrie and Jugram Haschwalth, killing them in the process.
The Aftermath
As the story draws to an end, the Goetei 13 find themselves under new leadership after Yamamoto's defeat, and possibly a restructuring of their priorities. This could go one of two ways... The Shinigami could continue the vicious cycle, seeking revenge for their leader's death, and starting another war against whoever is left of the Quincy Clan. Alternatively, Shunsui Kyoraku could take the high road and find a way to work alongside Wandenreich for the greater good.
Maintaining a balance of reishi is surely possible if everyone plays their part. The epilogue of the Bleach: Thousand-Year Blood War Arc shows a life removed from fighting Hollows since Seirietei and Hueco Mundo began working together so, in fact, the Shinigami have no need to persecute the Quincy anymore.