Forget me not

In a cold night a little boy stands next to another one in his late teens at the cemetery.
"Brrr ... can you just go already? I'll freeze to death if you take any longer"
"Suuuure, stay out of trouble while I'm gone~" Marshall winked to Gumball, floating to a grave with no name in particular.
"Wait, Marshall Lee! Will I... will I see you again?"
"Yeah Bubs"
"Pinkie promise?"
"Yeah... just don't forget me alright?"
"I promise"
In that very night both of them made a promise to not forget and to come back, but will they fulfill their promises? Even after being away for so many years? Ecen if they do, will they feel the same way towards each other as they used to?
This is an AU where Gumball is just a regular human and Marshall is a Vampire/half-demon/half-human.
I don't own the characters or the pictures