Warning: spoilers ahead for Episode 2 of The Flash Season 4, "Mixed Signals."
A brand new baddie is going after the Flash in Season 4, and he stands out from the first three supervillains of the series as a non-speedster. Instead, the Thinker uses his remarkable mind to outmaneuver his opponents. Unfortunately for Team Flash, the Thinker has decided that the Scarlet Speedster is an opponent worth targeting. While we haven't gotten to see a showdown between the two sides just yet -- in fact, Team Flash doesn't even know that the Thinker exists at this point -- the events of "Mixed Signals" have us wondering if the Thinker has been targeting Barry a lot longer than we thought.
The majority of "Mixed Signals" was relatively fun and silly as Team Flash adjusted to having Barry back after his time in the Speed Force. He and Iris weren't yet back on the same page, but we got to see some old school Flash-y shenanigans as Barry had some issues with the fancy features Cisco installed in his new Flash suit. It was in the final moments of the episode that we realized something was very wrong in the grand scheme of the series. After locking metahuman Kilgore up in a cell that would deprive him of using his abilities, Barry and Joe asked how he got his powers despite being in Silicon Valley at the time of the particle accelerator incident.
Kilgore declined to answer Barry and Joe, but the big reveal came anyway when the scene shifted from Iron Heights to the Thinker's high-tech lair, and we learned that the Thinker was creating the new metahumans on his own without the use of a particle accelerator explosion. Kilgore was referred to as "Subject 1," and a display indicated that there are still another 11 metahumans created by the Thinker getting in place to battle the Flash.
Of course, Kilgore was not the first metahuman to turn up who hadn't been in Central City for the particle accelerator explosion. Another such meta appeared back in Season 1, which could mean that the Thinker has been attempting to build his own metas to battle the Flash for the past couple of years, and only now is ready to put a grand plan into action. Remember Deathbolt?
Deathbolt technically first appeared in an episode of Arrow after Roy turned himself in as the Green Arrow. Believing that Starling City was without a protector, Deathbolt dropped by to rob some banks with his ability to absorb electricity and then generate plasma beams. He was ultimately captured and sent to Central City to be imprisoned by Team Flash in the pipeline, and the good guys discovered that Deathbolt was with the Opal City Police Department when the particle accelerator blew up, meaning that he did not gain his meta abilities the same way Barry and the other Central City metas did.
This was back during the first season of The Flash, and it seemed at the time that the show would soon address the mystery of how Deathbolt could possibly be a meta when he wasn't affected by the particle accelerator. The explanation never came, and many likely forgot about Deathbolt. After all, he died later in Season 1, and the show seemed to move on. Now that another metahuman has turned up who didn't get his powers from the particle accelerator, it's perfectly possible that The Flash will revisit the case of the last confirmed metahuman with the inexplicable power origin.
If Deathbolt was the product of the Thinker creating metahumans way back in Season 1, it would be a sign that the Thinker has been interfering with the superhero scene for a lot longer than we thought. Barry could have gotten himself on the Thinker's radar after Deathbolt was killed, or Deathbolt could have been aimed at Barry in the first place but the temptation of a Starling City without a masked protector was too tempting for a criminal to pass up.
Deathbolt as a meta created by the Thinker would answer the long-standing question of how he got his powers that has been lingering since Season 1; it would also mean that Barry and Team Flash are pretty screwed. The Thinker would have a head start of at least a couple of years on Team Flash. All things considered, the Thinker is truly shaping up to be Barry's most challenging supervillain to date, even if he's not the one responsible for Deathbolt's abilities. He can create metas, and that's a big deal.