The bitter feud between the Allen family and the Thawne family would span generations. Even in the 30th century, President Thawne sought to recruit Bart Allen in his revenge campaign against the Allens, since Bart was half-Thawne himself. When that failed, Thawne mixed Bart's DNA with Thawne genetic material to create a speedster clone whom he named Thaddeus Thawne. Whereas Bart grew in a hyper-accelerated world, Thaddeus' childhood was the exact opposite; His development was super-slow, which led the young speedster to become more calculating and methodical. Thaddeus was also taught to hate the Allen family, and Impulse in particular. In addition to this modification, Thaddeus' growth and development was slowed. This is in contrast to Bart's accelerated development (becoming physically 15 at chronological age 2). This was done to give Thaddeus more training and knowledge than Bart ever would. His mission as the "Reverse-Impulse" was to go back in time and replace Bart, but he was easily defeated.
Inertia later ambushed Bart and held him prisoner in a virtual reality, while he assumed Impulse's identity on earth. Once gaining Max Mercury's trust, Inertia led him into a dangerous trap within the speed force, intending to kill him. When Impulse raced to save his mentor, Inertia witnessed the love and trust between them. At that moment, Inertia realized that his whole life had been dedicated to a centuries-old hatred - leaving his own life cold and empty. Now enraged, Inertia ran off.
Appearing again after the One Year Later event, Inertia worked with Manfred Mota.  Inertia stated that his agenda involved stealing the speed of all other speedsters in order to become the next "Fastest Man Alive". His first targets include his old rival Bart Allen, who was now the latest Flash and the original Flash, Jay Garrick. After betraying Mota, Inertia used Mota's daughter, Valerie Perez, as bait in a trap he set for Bart. Bart escaped and successfully rescued Valerie. After this defeat, Inertia began to gather the Rogues for his next attack.
Inertia made a deal with Deathstroke. Due to Bart's encapsulation of the Speed Force, Inertia has been forced to inject himself with Velocity 9, a notoriously unstable substance invented by The Rival which allows the user to move at superhuman speeds. However, Inertia's Velocity 9 has been specially made by Deathstroke, but had shown no ill effects.
After being defeated when he confronted the captive Heat Wave. He recruited Heat Wave into his newest mysterious plan, telling him that he was talking about something that would "change the world". Getting rid of the Flash would "just be a bonus."
Bart foiled his plan, but Inertia made a getaway to his home era, where he began plans to build an army of Rogues.
He became a member of the new Titans East team in exchange for Deathstroke's help. He began the attack on the Teen Titans with Titans East teammate Match. Disguising himself as Impulse and Kid Flash, he defeated Robin and Raven, then toyed with Wonder Girl in Robin's secret facility. Ultimately, he let Match knock Wonder Girl unconscious. During the assault, Inertia mentioned that he was going to call himself Kid Zoom after Bart renamed himself from Impulse to Kid Flash, but decided to stick with the name Inertia.
He was romantically involved with his Titans East teammate Sun Girl.
He recruited Captain Cold, Abra Kadabra, Weather Wizard, Mirror Master, Pied Piper, Heat Wave, and the Trickster, and they began the construction of what he claimed to be a device to stop time on the site of the Getty Center. The idea being that once time was stopped they would have the freedom to commit crimes without being caught.
Once the plan was put into action, the Rogues attracted the attention of The Flash, but it was soon revealed that this was Inertia's intention all along: the machine they were building did not stop time, its function was to drain the Speed Force from the Flash (Bart Allen) and transfer it to Inertia, so he could regain natural speed powers and no longer be dependent on Velocity 9.
Though Bart did lose his speed, the Pied Piper and Abra Kadabra caught on to Inertia's betrayal and subdued him, before subduing the Flash. Inertia broke away in an attempt to reach the machine and prevent Bart's girlfriend from releasing the Speed Force, only to be tackled and beaten by a raging Flash. As he lay subdued, the other Rogues killed Bart.
Immediately after killing Bart, the Rogues turned their wrath on Inertia, blaming him for the entire fiasco. Inertia ran, but the arrival of the police forced the Rogues to flee before they could give chase, allowing Inertia to escape.
However, at the same time Bart was fighting the Rogues, Wally West, the previous Flash, returned to this plane of existence. Upon hearing of Bart's death, an enraged Flash hunted Inertia down. Though he thought of killing him, Flash decided to instead "do something worse." He used his abilities to slow Inertia's movements down to the point where he was totally immobile, essentially a living statue. He then placed Inertia on display at the Flash Museum, facing statues of Bart Allen as Impulse and Kid Flash. Though he can still think, see and hear in normal time, Inertia was then doomed to spend eternity in a state of near-total paralysis, staring at Bart's images (ironically enough, a variant of the fate that befell Zoom after attacking Linda for the first time). Wally describes it as being "forced to stare, with eyes that take a hundred years to blink... at the ghost of a man he could never be."
As he is about to be transferred from the Flash Museum to Iron Heights, Inertia is struck by a red lightning bolt, which frees him from paralysis. Hearing of the escape on the news, the Rogues decide to hunt him down as payback for being manipulated. After killing his guards, Inertia is about to attack Wally West's children, when he is stopped by the very person who freed him: Zoom, who wants Inertia to become a new Kid Flash. Zoom makes him put on Kid Flash's costume, telling him he will help in his quest of making The Flash (among others) "better heroes" by causing tragedies in their lives. Zoom shows Thawne how to affect the flow of time just as Zoom does.
Thawne later has a run-in with the Rogues who have been looking for him to extract their revenge. After the confrontation, the villain known as Libra arrives with the Weather Wizard's baby son, saying that if the Weather Wizard does not join his cause he will kill the child. Before Weather Wizard can make a choice, Thawne kills the baby. This leads to Thawne changing his costume and calling himself "Kid Zoom," along with the loss of Zoom's powers. Thawne is beaten by the Rogues and killed. The Rogues then leave a message next to Thad's corpse: "Tell the Flash we are even - The Rogues."
- Personal Time Manipulation: Thaddeus has the ability to alter time relative to himself, as opposed to utilizing the Speed Force like most of the DC Universe speedsters do. He can apparently use this ability to move at "speeds" rivaling those of even Wally West, fastest of the Flashes, and usually, "faster" than the speeds that even Wally can muster in most cases. Since Thaddeus isn't actually moving at super speed (rather, he is greatly slowing down Time relative to himself, and can make himself so "fast" that even most of the Flashes look to him to be moving in slow motion.) The temporal nature of his speed allows him to avoid the usual problems encountered by other Flash-type speedsters (friction, seeing and hearing at such near-light speeds, etc.), whose automatic and unconscious use of the Speed Force overcomes those problems. As he is moving at a normal velocity, and the rest of the world is "slow", those hindrances simply do not affect him. This aspect also means that he is unable to become intangible like other speedsters can by vibrating their molecules at certain frequencies, giving them a distinct advantage. He can use his manipulation of time to speed up the molecules of an object or being causing them to vibrate till they explode. He also has the power to steal someone else's personal time by pushing them backwards down their own timeline.
- When asked as to who should receive credit for creating Inertia, Ethan Van Sciver stated: "I wouldn't accept credit for that. I think if a pie chart were made of who created Inertia, is would be built of these percentages - Grant Morrison: 25%, Todd Dezago: 50%, Mike Wieringo (who designed the original Impulse costume, which was reversed for the sake of Reverse Impulse) 20%, Me: About 5%, for making him green and black, and giving him blonde hair."
- What Grant Morrison contributed remains unknown.
- 31 Appearances of Thaddeus Thawne II (New Earth)
- 20 Images featuring Thaddeus Thawne II (New Earth)
- 5 Quotations by or about Thaddeus Thawne II (New Earth)
- Character Gallery: Thaddeus Thawne II (New Earth)
- Inertia at dccomics.com
- Inertia (DC Comics) at Wikipedia.org
- Thaddeus Thawne II (New Earth) at Flash: Those Who Ride the Lightning
- Inertia at Titans Tower
This character is or was primarily an enemy of the Teen Titans, the Titans, or any of the other various Titans incarnations. This template will categorize articles that include it into the "Titans Villains" category.