Warning: spoilers ahead for Episode 17 of The Flash Season 4, called "Null and Annoyed."
The Flash has dealt blow after blow to Team Flash in Season 4 thanks to The Thinker as the latest supervillain. Outthinking the good guys time and time again, Team Flash's greatest victories have basically been stopping The Thinker from murdering a couple of characters after failing to save a bunch of others. They finally made strides toward beating him at his own game when Harry invented his own version of The Thinker's thinking cap. While the cap has already allowed Team Flash to make some strides and save some lives, "Null and Annoyed" revealed that the effects of Harry's thinking cap could be devastating. After the events of the latest episode, Harry could be a lot more dangerous.
Harry has spent Season 4 struggling with the fact that The Thinker is smarter than he is. Accustomed to being the smartest man in the room, The Thinker has been just about the worst nemesis for Harry. The thinking cap was always something that could do permanent damage to Harry, but he simply didn't mind if it meant beating The Thinker. "Null and Annoyed" showed that Harry was already getting more angry and volatile than he was before, and the tag indicated that he could be approaching the level of ruthlessness of another character: Eobard Thawne. Harry went down into the time vault to store the thinking cap; while there, he activated Gideon.
No, not the Legends of Tomorrow version of Gideon who has been traveling through time and space with Sara and Co. This was Original Recipe Gideon who helped Wells 1.0/Eobard Thawne in Season 1 with his nefarious plans. Harry is obviously a different character than Thawne and he's never seemed especially villainous, but we have reason to worry. After activating Gideon, he told her/it that a lot had changed since last they spoke.
Now, if Harry had beens speaking to Gideon on a regular basis, his comment wouldn't be all that troubling. He'd had a big day in "Null and Annoyed," and plenty would have changed even if they'd only spoken hours before. What was troubling was Gideon's comment that they hadn't spoken in more than a thousand days, and that was well before the Harry version of Harrison Wells was spending his time at Earth-1's STAR Labs.
Is this a sign that the Harrison Wells who has been in The Flash Season 4 lately isn't Harry, as we thought? Does it point toward the thinking cap turning him into an evil version of himself? Should we be nervous that Gideon recognized him? The Flash showrunner Todd Helbing has already said that using the thinking cap is "a slippery slope" for Harry, and his discovery of and interaction with Gideon could be a sign that he's going full villain.
Or maybe he'll stay aligned enough with Team Flash that he'll be an asset rather than an antagonist. We'll have to wait and see. Tune in to The CW on Tuesdays at 8 p.m. ET to catch new episodes of The Flash. Our rundown of superhero TV dates can point you toward when to watch other comic-based series. Our midseason TV schedule and summer TV guide can help you plan your viewing lineup for the not-too-distant future, and our breakdown of network TV renewals and cancellations can fill you in on which shows have and have not gotten the axe in the 2017-2018 TV season.