"Mercury Falling, Part Four: Bart Allen's Evil Twin": When Impulse pushed the Mudbug back into its own dimension, Inertia switched places with him. Now Inertia continues his impersonation of Impulse, but while he looks the same, there are differ
- It's not him! It's not Bart! It's Inertia!!
Appearing in "Mercury Falling, Part Four: Bart Allen's Evil Twin"
- Glory Shredder
- The Reverse Flash (Flashback only)
- The Mudbug (Flashback only)
- White Lightning
- Green Cigarette
- Gaspar the Lawyer
- Dox (Flashback only)
- The Flash (Barry Allen) (Flashback only)
- Young Justice
Synopsis for "Mercury Falling, Part Four: Bart Allen's Evil Twin"
When Impulse pushed the Mudbug back into its own dimension, Inertia switched places with him. Now Inertia continues his impersonation of Impulse, but while he looks the same, there are differences in behavior which Thad Thawne cannot cover up completely. Max Mercury appreciates a much more focused Impulse and both Bart's friends at school as well as members of Young Justice are fine with his change in character. Only Carol Bucklen is suspicious regarding her friend. When Max is praising Impulse's good work, Thad feels very good because nobody has ever been proud of him. With all the love he receives, he even thinks about not continuing his plan of killing Max.
At home, Thad finally has figured out how to fool Bart's dog as well. He constantly feeds him with dog treats and informs Helen and Max that he will name the dog Ivan (in honor of the behaviorist Ivan Pavlov). After Max and Impulse have left to visit Dr. Morlo, Carol sneaks into the house to find some clues that might back up her suspicion regarding Bart. Looking at a framed picture, Carol realizes that Bart currently is not wearing his costume ring although she believes he would never take it off. And then she also finds some hair dyer. She rushed down to Helen and tells her that Bart seems to have been replaced by Inertia.
In Morlo's lab, Thad has passed all final tests so that the scientist sets up everything for Impulse and Max to jump into the Speed Force. As soon as they are gone, both Helen, Carol and the real Impulse turn up looking for Inertia.
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