Rusty and Ryder are twins separated at birth.
They're both Child Prodigy/Mr. Fixit boys who are around ten years old. Not to mention in the pilot made by Guru Studio, it's clear that Rusty's character model is an edited version of Ryder's. Also, Mrs. Rivets has brunette hair like Ryder.Maybe they're twins and newborn Ryder was given to a woman/couple living in Adventure Bay.
- Or they could be cousins who are the kids of identical twins, resulting in the similar appearances.
- That crossover short with Paw Patrol confirms they exist in the same universe. It wouldn't be surprising if Ryder and Rusty were close.
Frankie is an Irken.
Possibly even Zim's son! Obviously, Frankfurt is his SIR unit, whereas his Doomlord helmet is a special limited-edition model PAK.