While the family argues, Dennis sadly flees the hotel and enters the forest with Winnie in tow, hiding in her treehouse. They are attacked by Bela, who mistakes Dennis for a human. When Bela injures Winnie and threatens to destroy the hotel, Dennis' anger causes him to instantly grow his fangs and his vampire abilities manifest. He begins to fight Bela, who calls his giant-bat minions. Drac, Mavis, Dennis, Johnny, the rest of the monsters and Johnny's family team up to defeat his minions. A livid Bela then attempts to kill Johnny himself with a stake. Having been won over by Drac's claim that humans are harmless now, Vlad shrinks Bela and tells him never to bother his family again. Bela then flees.

Is it true that does dennis become a vampire in hotel transylvania 2?
yes