A [[http://www.fanfiction.net/s/7525288/1/Old-Meets-New fanfic]] made by [[http://www.fanfiction.net/u/80745/RockSunner RockSunner]], a crossover for [[WesternAnimation/ScoobyDooMysteryIncorporated Scooby-Doo! Mystery Incorporated]].
This is a Scooby-Doo to Scooby-Doo cross-over in which the original ''ScoobyDoo'' Mystery Incorporated (from ''Scooby-Doo, Where Are You!'' to ''What's New, Scooby-Doo?'') meets the new ''WesternAnimation/ScoobyDooMysteryIncorporated''. It has spoilers to the end of the latter series.
This is a 32-chapter work and it is now completed.
!!This fanfiction series contains examples of:
* AlternateUniverse: the original continuity is an AU to the Crystal Cove one.
* AlternateUniverseFic: A WhatIf with the insertion of the second Mystery Incorporated after the end of the first season of SDMI.
* BigDamnHeroes: Cassidy and the original Shaggy [[spoiler: save Marcie from Pericles in a CurbStompBattle using salvaged villain tech. Subverted because it was all engineered by the Evil Entity, as Marcie learns in a NiceJobBreakingItHero moment. However, thanks to this change Marcie survives and enters the new universe with memories intact.]]
* CassandraTruth: Mr. E, warning [[spoiler: Casssidy and "bad" Shaggy that they cannot face the Evil Entity while corrupted. He is not believed, leading to a FaceHeelTurn by both.]]
* ChekovsGun: The Dark Lilith suit is not used on Mount Diabla, but Marcie talks about building a "fight-or-flight suit" [[spoiler: which is used by Cassidy in the dramatic rescue of Marcie.]]
** Coolsville Velma calls herself "Dace" as a nickname to distinguish herself from her counterpart.
*** Dace is commonly believed to be Velma's middle name. She was called "Velma Daisy Dinkley" in ''Scooby-Doo! Curse of the Lake Monster''. Velma in this story lampshades the MemeticMutation that turned "Daisy" into "Dace."
** Dace mentions potential boyfriend Winsor from ''Legend of the Phantosaur''. Shaggy also has a minor reaction to the word "bad", which he shakes off. [[spoiler: He later learns how to activate "bad" mode again, with the help of Cassidy Williams.]]
* FixFic: the old Mystery Incorporated gets the new one back on track faster after their break-up, [[spoiler: with the exception of Daphne, who may take longer to rejoin them, giving Hot Dog Water a longer time in the group.]]
* PoweredArmor: An exoskeleton for [[spoiler: the old Scooby is made from Fright Hound spare parts. Shaggy has the Space Kook armor, and Cassidy has the Dark Lilith suit. Together they form a super SwatTeam.]]
* TriggerPhrase: A backdoor [[spoiler: into the Fright Hound combat program that can control the comatose original Scooby: "Nibiru Nibiru Nibiru". Foreshadowed when Pericles tries to use it, too late, then used for real by the Evil Entity.]]
* YouKillItYouBoughtIt: After killing [[spoiler: Pericles]], it is the fate of [[spoiler: the original Scooby]] to become [[spoiler: the host body for the Evil Entity]].