Donnie and Pidge worked together in the Castle of Swan Lake not only as lovers but as husband and wife. Donnie and Pidge got married after Shiro and Matt got married and ruled Krolia's kingdom and a year later, Donnie and Pidge had a son named Matthew and still called him that in order not to cause confusion between Pidge's brother and son

Matthew was helping his parents create a robot and when they finished, Donnie gave the robot the name "Metalhead" as Matthew says "This has to be the best robot ever, Dad" Donnie scoffs "Don't know about that. I've invented a lot of things before I met your mother" Matthew says "No other inventor can be any better than you and Mom" Pidge laughs "Well, Metalhead may be an invention but he can also be a friend and can do anything"

Matthew smiles and says "We should go on an adventure together. Maybe even take Metalhead places he hasn't been before" Pidge smiles and says "That's an amazing dream, Matthew" Matthew asks "Did you and Dad have dreams?" Donnie replies "Well yes, we did. I dreamt of creating things nobody's ever used before and your mother dreamt of being a scientist but the most important dream of all is you, son"

Pidge smiles and says "Sure, your father and I invented many things and discovered more worlds but the greatest invention we have in the world is you" Matthew laughs "That's great Mom but I wanna ask you guys something" Donnie says "Go ahead" Matthew asks "Any chance you could invent a sister?" Pidge replies "We'll think about it" Matthew says "Okay" Donnie agrees "But don't worry, your mother and I will get you something more than a sister" Matthew asks "Like what?" Pidge and Donnie reply "A pet"