Inertia

Thaddeus Thawne, known as Inertia, is a clone of Bart Allen engineered to serve as his dark counterpart — possessing the same speed-based legacy but twisted toward villainy, making him a dangerous enemy to the Flash family.

A villain born in the thick of DC's Modern Age, Inertia made their mark with a debut in Flash: The Fastest Man Alive #7 in 2007, courtesy of a creative team that includes Danny Bilson, Paul Demeo, Ron Adrian, and Art Thibert. The pages this character haunts are packed with heavy hitters — Thaddeus Thawne, Robin, Wonder Girl, Raven, and Batgirl all share the spotlight across appearances in Teen Titans and Tiny Titans alongside that memorable Flash debut. With only ten catalog appearances, Inertia is a compact, intriguing presence rather than an omnipresent one — the kind of character that rewards the curious fan who digs just a little deeper into the DC Modern Age's rich, interconnected tapestry.