Alexander is the familiar (pet) of Satanichia. He is a dragon puppy that can be summoned with a spell by Satania. Unlike Vigne's Chappy, it's unknown how Satania found him.
Alexander has a tiny and chubby appearance, with his most catching appearance is his protruding navel and constantly blushing cheeks. He is a cream-colored dragon with his stomach area is colored white. His tail has a leaf-shaped end, tiny wings, small two yellow horns and ears that shaped like a dog. Unlike the stereotypical dragons, Alexander's appearance is considerably cute.
His personality is similar to a real puppy, he makes barking sounds and loves to play and fly all around. He is a good pet since he is eager to please Satania and loyal to her as well.
Alexander is also a coward as he pretends to die when seeing Chappy (although this can be considered as an intelligent move since Chappy is massive compared to him and he is still a puppy) and despite being a dragon, he does not have the pride of a typical dragon.
- Satanichia McDowell Kurumizawa: They have a good relationship with each other, as owner and pet (Satania prefers calling him "Familiar" instead). With Alexander is obedient and loyal to her, Satania herself also treats him kindly as she praised Alexander despite his failed flame breath (only smoke came out). Although it is unknown how they met and how long they have been together, they are very close with each other. Satania is also proud with him, as she said Alexander will not lose to Chappy although he rather plays dead to trick Chappy.
- Vignette April Tsukinose: They only met once briefly when Satania is playing with him and Vigne is bringing her pet, Chappy for a walk. They also didn't interact with each other, but knowing that Vigne has Chappy, he may develop slight fear for her.
- Chappy: They met when Satania and Vigne accidentally met whey Chappy running chase a butterfly and Chappy later accidentally uses his fire breath in excitement for meeting Satania and Alexander. Intimidated by his size and power, Alexander opted playing dead instead to make sure the hell hound didn't go after him.
- It is unknown since when Satania owns Alexander, but since he is still a puppy they may just met each other recently or they may have known each other for some time but dragons age slowly, compared to hell hounds.
- Alexander have flame breath like Chappy, but his power is still low that his attack failed.
- Since Alexander acts like a dog in the human world, this maybe the reason why Satania actually loves the dog in the human world.
- Although he is Satania's familiar (pet), it's unknown about his relationship with the Kurumizawa family.