When Johnny first entered the hotel, Dracula thought that the backpack belonged to an other monster unstil Johnny turned around. Drac later used the backpack to hide the "human" until he can find away to get him out of the hotel, without any of the monsters knowing. When Drac hid him in the closet, he checked the Backpack for "weapons" and pulled out one of Johnny's unwashed shirts; and when he got the idea to dress the human as a stine, he got Johnny to leave the backpack in the closet.When Quasimodo Wilson tried to cook the human, Johnny asked him if he could have time his backpack before he dies; but Drac stepped in to save him. After Johnny's secret was reviled and he left the hotel, he fetched his backpack back from the closet and took it with his as he left. After Drac had brought Johnny back to the hotel so he and Mavis can be together, he gave his daughter her own backpack, so she can place her belongings in it as she goes to see the world. She wasn't sure why her father was giving her one, but when Drac turned it around to revile Johnny and gave her back the old postcard, she knew that he was letting her leave the hotel and follow her dream.
At Johnny and Mavis' wedding, Johnny made his backpack his "best man", as he "let" it be in some of the Wedding photos and bear the rings. When Johnny and Mavis were seeing Mike and Linda in California, and before Linda took them to the room that she had prepared for them, Johnny patted his backpack like he was patting someone's head, after he had placed it down in the living room. When Mavis had found out that "something was wrong" and told Johnny that their heading home, Johnny replies "I'll go wake up my backpack," before the two headed to the air port. After the two found out that they wouldn't get a direct flight to Transylvania, Mavis turned herself into a bat and used her bat feet to hang onto her husband's backpack as she lifted him up into the air.
When Vlad was on his way to the hotel for Dennis's birthday, Drac told his son-in-law that Vlad will "eat" his backpack if Vlad finds out that he and his family are humans and that the only way to save his backpack was to turn Dennis's birthday party into a Monster masquerade, so he and his friend can dressed themselves up as monsters.