The Knights and their patronus
Disclaimer: Same as JKR I'll not give in the story a patronus to the future Death Eaters, but I came with every patronus to each of them. Many times I'll describe them when they are adult, because I'll put the patronus class in their last year.
Walburga: a dog. Meaning of loyalty and protection, this describes Walburga especially as a mother: she is loyal and protective, even if it's in the wrong way, but her means are good.
Orion: a cat. Meaning of liking spending time alone and being by themselves, this is Orion a lot in his adulthood. He can't be alone, but whenever he can he takes quality time for himself.
Alphard: an elephant. A strong connection with those around then, friends and family. He doesn't follow a lot the crowd, and he is unique. Alphard is somebody who will be in the neutral side of the First Wizarding War, while everybody else in his family will join a side.
Cygnus: a white swan. While the swan is the meaning of grace and love, Cygnus he loves fiercly people he is close to. He gives positive energy freely especially in his teenagers years and early adulthood.
Antonin: a brown bear. A symbol of Russia (Antonin's home country), the bear means having a wild and free heart, and in need of little help, with difficult life problems. It recalls to Antonin's childhood and teenagers years.
Tom: a snake. Symbol of his household and House, it also means duality, wisdom and circle of life and death. Tom is a Christian Catholic person (in later life he will consider himself atheist) and in this religion the snake is symbol of evil.
Lucretia: a moth. Meaning of a connection to transformation and embracing the unknown. While the Moth means rebirth and inner strength, in Lucretia's case it means fragility and vulnerability, as she tends to be easily swayed.
Druella: a dolphin. Meaning of a person intelligent, social and expressive. Druella is a social person and expressive, she never has to stay quiet if she has something to say.
Mathilde: a wolf. Lone and solitary, and aptitude for combat. But it is also great in packs. It balances the two personalities. The wolf represent feared and mystery. It describes Mathilde's adaptability for fighting both alone and with other people.
Icarus: a hyena. Symbolizes a person who is cunning, clever and smart, often using a humorous or silly facade to hide their true motives and outwit others. Especially post August 1945 this is Icarus' description.
Reinhard: a wild boar. Symbol of strength, courage, loyalty, and a warrior's spirit, indicating someone who is strong, noble, and fierce when challenged, yet also grounded and honorable. Reinhard is the most physically strong within the Knights.
Evan: a fox represents cunning, resourcefulness, quick thinking, adaptability and solving problems by going out of the box, it's also a good definition for pranksters.
Abraxas: an peacock. Symbold of natural show off, eccentric, but suffering of making often poor judgement call. Wonderful entertainer, it describes Abraxas his whole life.
Diana: an eagle. Symbol of a person being bold, free and dominant. They know what they want and how to get them. Stubborn, they open up to close people only. Diana doesn't like to let people telling her what to do, she prefers her clear path.
Maxwell: a hummingbird. Symbol of flirtation, charm and vital energy, it's Maxwell whole life as a charmer (hence his nickname within the Knights)