YMMV / Fate Grand Order Event 20 Deep Sea Cyber Nirvana Seraph

• Complete Monster: The Beast-III R incarnation of Kiara Sessyoin was once an innocent nun and therapist staffed in Seraphix, but after Zepar inhabited her body and whetted her darker personality, she let herself become much worse. Assimilating the Demon God Pillar and throwing it away after torturous servitude, Beast-III R took over Seraphix using her dark charm and charisma, culminating in using its Planetarium to torture 128, near-dead young Masters over and over into summoning Servants that repeatedly killed one another in a recreation of the Moon Holy Grail War. Obtaining enough power to become Beast III-R, the Demonic Bodhisattva, Beast-III R plunged the digitized Seraphix into the Marianna Trench in hopes of reaching the Earth's core, fusing with it, and turning the planet into a horrid perversion of nirvana. Enslaved by her own ego and thirst for pleasure, Beast-III R is nothing more than a self-absorbed, narcissistic hedonist who viewed all of humanity as mere tools to satisfy herself.
• Magnificent Bitch: B.B. is a "Moon Cancer" Servant created by the Moon Cell as a perfect copy of the original assigned to stop the Demon God Pillar Zepar and Kiara Sessoyin. A perpetually-smiling, grandiose Wild Card who can shift from playful and teasing to manipulative and treacherous on a whim, B.B. instigated Chaldea's arrival to Seraphix. Operating under the pretense of a Killer Game Master making events as cumbersome and dangerous as possible for the Master of Chaldea and their allies, B.B. in fact was clandestinely making preparations to overthrow and defeat Beast III-R. Switching out the Master's allies mid-Rayshift, such an act paid off when each of them contributed to victory in their own ways, particularly that of EMIYA Alter. Her impish sadism belying her crafty nature, B.B. managed to move all the pieces into place and manipulate all the players of her game before anyone realized.
• Unexpected Character: The manga adaptation has the Big Bad of the Fox Tail manga Kazuradrop working for BB.