-Few years later-

Marshall walked into the living room and looked around for his boyfriend. Barnaby jumped out from behind the door and hugged him. They both laughed and gave each other kisses. "So hows Fionna and BMO?" Marshall asked. "They are great! they are engaged now" Barnaby smiles.

"Thats great im so happy for them" Marshall smiles. Barnaby nods and rests his head on Marshall's shoulder. "Hey baby?" Marshall asks. "Yes?" Barnaby looks at Marshall. 

Marshall moves on one knee and grabs Barnaby's hand. Barnaby's tears slid down his cheeks and he smiled. "Will you marry me?" Marshall asks. "Yes!" Barnaby exclaims and hugs him tightly. 

They later got married, and had a child.

The end <3