Boris Dracula was the son of Ivan Dracula, the older brother of Olga Dracula, the nephew of Count Dracula, and the same age as Mari Dracula and the older cousin of Vladimir Dracula, and Ingrid Dracula, When he first appears however, unlike Vlad, he is only days away from his transformation, and is beginning to show signs of vampirism when viewers first see him. He flies in his sleep, and sometimes succumbs to bloodlust.
He has involuntary moments when he uses his powers: in the third episode of the series, he accidentally "flames" a book that was supposed to contain "A painless cure for vampirism" when he is frustrated by not being able to find a clear definition early on. Thankfully his use of powers before his transformation is brief.
In the episode "When Vampires Go Bad", Boris makes one final appearance, disguising himself as the vampiric community's "judge, jury and executioner", slaying the Grand High Vampire in order to frame and execute the Count. He tries, before succeeding, to wear the Grand High Vampire's crown, but then gets himself turned into dust by it, as it is revealed that only one who is worthy of the title may wear it.
Much like Vlad, Boris did not wish to be a vampire. A physically weak asthmatic, this seemed to be more out of cowardice than a desire to fit in. He was a very shy, nervous boy before he transformed in front of the blood mirror. He became a handsome blood-sucking, power-crazy maniac who had completely lost all sanity, even to the point of draining power from his father and his uncle, the Count. Although the "new" Boris was insane he still maintained certain elements of the old Boris. He continued to make jokes (although nastier) and wished to share power with Vlad.
He develops a friendship with Vlad, sharing his room, and early on confides his fears of being a vampire. He seems to continue to regard Vlad as a friend and even after Vlad "betrays" him by giving his father and uncle their powers back, he does not seem overly angry. He tells Vlad that when it's his turn he'll become just as evil as him.