Rudolph Sackville-Bagg has problems. Not only is he thirteen years old and a vampire but his whole family is threatened with extinction by the nefarious vampire hunter Rookery and his assistant Maney. Meanwhile thirteen-year-old Tony Thompson, who loves old castles, graveyards and vampires, is on vacation with his family in Black Forest, Germany. When the two boys meet, Rudolph brings Tony along on the adventure, which takes the two boys to Transylvania and brings their two families together, helping them overcome their prejudices against each other.
This film provides examples of:
- Adaptational Jerkass: It takes Frederick much longer to warm up to Tony than in the live-action, with him outright attempting to attack Tony when they first meet.
- Age Lift: Rudolph and Tony are both aged up to thirteen. In the original book they were 10 and 9 years old and in the 2000 film they were both 9.
- Going by this, Gregory is also aged up from his canonical age of 13.
- Alliterative Name: Tony Thompson.
- Birthday Hater: Rudolph doesn't like his, since he's celebrated it three hundred times before.
- Failed a Spot Check: It takes Gregory a few seconds to realise that Tony isn't a vampire, despite him lacking blue skin and fangs and being dressed in modern clothing.
- Heel–Face Turn: Maney tells Rookery that he needs professional help and leaves him in the climax.
- Helicopter Parents: Frederick doesn't want any of his family leaving the catacombs and is annoyed with Rudolph for going outside, even though he didn't go farther than a few metres at most. All three of his children are shown to chafe under these restrictions, with Gregory and Rudolph going out anyway and Anna complaining that "Father doesn't want us doing anything." However he does have good reason to fear for his children's safety.
- Hidden Heart of Gold: Gregory.
- Interspecies Friendship: Tony (human) and Rudolph (vampire).
- Missing Reflection: Rudolph confirms for Tony that vampires don't have them.
- Right for the Wrong Reasons: The couple who run the bed-and-breakfast are clearly worried that their guests might be vampires. At the end of the film Tony brings Rudolph and the rest of his family to stay as guests at the castle.
- Surprisingly Realistic Outcome: Tony is a fan of vampires. However he's still pretty scared to have one in his room and his first reaction to Rudolph's appearance is to hide and then try to run away.
- Surrounded by Idiots: Inverted. Rookery's assistant Maney is more levelheaded than his boss and tries to act as his conscience and Voice of Reason. What is played straight about this trope is that Rookery is sometimes irritated by him.
- Vegetarian Vampire: As in the live action film, the Sackville-Baggs (except for Gregory) stay away from mortals. When Rudolph does need blood, Tony takes him to feed on a cow. However, Rudolph implied that they have fed on mortals in the past.
- Weakened by the Light: Strong light hurts and weakens vampires, sunlight will kill them.
