This is based on opinion. Please don't list it on a work's trope example list.
Tearjerker / Scooby-Doo on Zombie Island
During the opening, Daphne mentions in an interview that even though she, Fred, Velma, Shaggy and Scooby ultimately got tired of solving Scooby Doo Hoaxes and (for the most part) went their separate ways, she and Fred still miss Velma, Shaggy and Scooby. While currently working as airport security personnel, Shaggy and Scooby happen to witness this while on-the-job, and admit to feeling the same way.
Turns out that the zombies are not the bad guys, their souls just couldn't rest until the real monsters were finally put to justice and the life force that was consumed from them were freed.