Big Eater: An instance of Fridge Brilliance: Saya only receives just enough blood to keep from getting thirsty, but her body still needs more energy. Human food isn't quite enough to match up to blood, which is why she burns through calories so quickly and has to eat so much.
Boyish Short Hair: From at least the Russian Revolution onward. According to the Adagio manga, after having a nightmare of Diva's rampage at the Zoo and mistaking her reflection for Diva, she freaked out, messily chopped off her hair, and then had Haji fix it, resulting in its current style.
Death Seeker: Her entire reason for living for over a century was to kill Diva to correct her mistake, and then kill herself afterwards. In the final episode, Haji and Kai persuade her to not do the latter.
Easily Forgiven: For her actions during the Vietnam War. Granted, she wasn't in her right mind at the time, but still, she killed dozens of innocent people, including women and children, chopped off Haji's arm, and personally slew David's father, and all she gets is a slap on the wrist. Almost makes the Red Shield seem like a bunch of hypocrites for giving her so much slack while they are convinced that Diva is an irredeemable monster.
Locked Out of the Loop: When she is recruited back into the Red Shield while amnesiac, both Haji and David repeatedly refuse to tell Saya anything about her past or mission, insisting that she has to remember on her own. Of course, this results in Saya being forced into horrific bloodshed and countless Break the Cutie moments without even knowing why, but either way...
Spoiled Brat/Spoiled Sweet: Starts out as the former due to her upbringing under the first Joel Goldschmidt, but mellows out into the latter through her friendship with Haji.
Sympathy for the Devil: Despite her long-running mission to kill Diva, Saya still feels sorry for her due to her Dark and Troubled Past. When she finally succeeds at killing her, she considers it a hollow victory and breaks down in tears.
Undying Loyalty: To Saya. Deconstructed as well, since in the finale, he would have just stood by and let Saya kill herself if Kai hadn't stepped in.
Willfully Weak: Suppresses a lot of his natural abilities because when Saya first saw him use them, she was terrified. He also basically starves himself of blood, which is why he is not as strong as the other chevalier, though if he tapped into his natural abilities and had enough blood, he would probably be second only to Amshel.
Ambition Is Evil: The whole reason he betrayed the Red Shield for Diva's group in the first place is because he wanted to make his research on chiropterans public, which the Red Shield forbade him from doing.
Armor-Piercing Slap: Delivers one to Saya after discovering that Saya's next hibernation period is coming and Saya didn't think it important to tell anyone.
Demoted to Extra: Only appears as a very minor character in the manga, first bullying Saya because she's jealous that she lives with Kai, then recruits Saya to be in the school play in hopes that Kai will come and watch.
Spoiled Sweet: She's remarkably nice considering her dad's status and wealth
Stalker with a Crush: Mao steals four million yen from her mob boss father's untraceable cash stash to follow Kai across the world.
Tsundere: Dere for Kai, tsun for everyone else, especially Okamura.
What the Hell, Hero?: Along with the Armor-Piercing Slap moment mentioned above, Mao also chews Saya out for not bothering to tell anyone her next hibernation cycle is approaching when they've been working their butts off to help her.
Yakuza Princess: Her dad's a mob boss and she certainly carries herself like a princess.
Tropes associated with Okamura:
Intrepid Reporter: He chases the vampire monster sightings across continents to be like his father.
All Women Love Shoes: Rare anime example. She sees a guy with cute sneakers, kills him, takes said shoes and wore them for the rest of the episode.
A Million Is a Statistic: Quite a few people lost sympathy for Diva after she raped and killed Riku. Sure, never mind that she's filled entire graveyards over the past century. Even then, she won back some favor because of her love and compassion for her unborn babies.
The Dreaded: Is this to the Red Shield to the extent that, when he meets her face-to-face in Episode 24, Lewis is so thoroughly intimidated by her that he falls back on his ass in fear, and is extremely relieved when she chooses to pursue Saya over eating him.
Motive Rant: Gives one to Saya right before they fight at the opera house, in the hopes that her sister would agree and they wouldn't have to kill each other.
Muscles Are Meaningless: She is the exact same size and weight as Saya, but is shown to be powerful enough to punch David across a room and then toss Saya clean through a brick wall without even trying. As the other Chiropteran Queen, and a well fed one to boot this is justified.
Roaring Rampage of Revenge: The very first thing that Diva does when Saya releases her from the tower is butcher Joel I and the patrons at his birthday party in retribution for all of the pain and suffering Joel put her through.
Undying Loyalty: Towards Diva, by instinct. Though it is possible for them to overcome this.
Tropes associated with Amshel:
Ambition Is Evil: And how. Everything he does is because of his desire to find out everything he possibly can about chiropterans, and if that means overstepping all kinds of moral bounds and nearly causing The End of the World as We Know It, it's a small price to pay.
Bigger Bad: He's the one who turned Diva into the monster she is, and has spent the last century planning to convert humanity into chiropterans using Diva. He is the only one of Diva's chevaliers to outlive her... for a minute or two.
Creepy Crossdresser: First appears disguised as an old woman, then kills a Red Shield operative and spends the next few episodes disguised as her. And in the last few episodes, he arrives for the final battle disguised as Diva to buy time against Saya.
Curb-Stomp Battle: His initial battle with Saya in the present day. It ends with Amshel crushing Saya's arm and breaking her sword.
Harmless Electrocution: Averted. After being impaled on the Chrysler Building's spire, Amshel is fried by a lightning bolt attracted by the spire's point. He survives (barely) but his healing factor has him stuck between his human and chiropteran forms when he returns to finish his fight with Haji.
Taking You with Me: When Haji uses Saya's sword to kill him for good just before the MET is bombed, right before he completely crystallizes, he impales Haji with his claws and traps him, rendering him seemingly unable to escape the bombings.
Undying Loyalty: Towards Diva. He later feels this way towards Saya, to the point where he betrays Diva (though he still admits he cares about her.)
War Is Hell: His experiences during World War I was one of his main reasons to become a chevalier, so he could be free from seeing humans kill each other, only to discover that chiropterans are just as bad.
Worst Aid: After Saya pulls off a Deliberate Injury Gambit to kill Karl, Solomon stops her from pulling her katana out of her stomach, warning her that she could potentially damage her internal organs if she forces the blade out before quickly and cleanly yanking the sword out of Saya's body himself. If not for Saya's Healing Factor, she would have bled out right then and there.
Taking You with Me: In his and Saya's final fight, he has Saya at his mercy and attempts to completely drain her of blood, knowing this would kill him as well, so they could die together. Saya doesn't go for it.
Tragic Villain: Karl was made a chevalier against his will because Amshel wanted one to experiment on.
Irony: After an encounter with Saya leaves him fatally wounded and unable to regenerate, he's forced to get Schiff implants to stay alive. This means Diva loses interest in him for the same reason he scorned the Schiff.
Mercy Kill: After seeing that Diva has died and lamenting on her own foolishness, he reverts to Chiropteran form and gently asks Saya to kill him, since he would essentially be living an empty life of immortality. Saya grants his last wish. ... although he's later seen to have survived the encounter and disguised himself as a reporter.
Bittersweet Ending: After enduring all of the struggles and losses she and her band of fellow Schiff went through, she ends up being the Last of Her Kind. On the bright side, she's finally got to see Okinawa and receives medical treatment from Julia to ward off the Thorn.