Spoilers below for the latest episode of The Flash, so be warned.
Tom Cavanagh is one of The Flash's biggest weapons when it comes to performance versatility, and Season 4 has taken his Earth-2 genius to some dark places. Harry Wells has spent part of the season's latter half unwittingly self-sabotaging his own intelligence with his homemade helmet, and his brain misfires have gotten so bad that even the multi-dimensional Council of Wells is booting him from their ranks. Star Grant Gustin thinks it's a heartbreaking arc, and its effects aren't just tethered to Harry, but the entire team. In Gustin's words:
While The Flash obviously isn't going to match the dramatic highs and lows of award-winning indie dramas explicably about Alzheimer's patients, Harry's storyline does have similar touchstones. His only want and need is to return to his natural thinking state, but his mind is allowing anything but, which can easily cause rifts both personal and professional. But while part of the tragic nature of mental diseases is that the sufferer isn't always cognitively aware, Harry is plagued by the knowledge that his own creation, and adamant use of dark matter, is what sealed his fate. What's more maudlin for a superhero show than an ego-heavy genius facing mental degradation?
As Grant Gustin put it to EW, it's not just about sympathizing with Harry over his situation. One big reason he's remained on Earth-1 is to help the team take down Clifford DeVoe, and had he been more responsible with his helmet development, he might have been successful in ways that didn't involve his own brain cells being sapped. And now, instead of being able to fully focus on bringing The Thinker to justice, Team Flash also has Harry's situation to devote resources to. And as we know, all it takes is one slightly wrong turn for DeVoe to achieve full advantage all over again.
Of course, it's also pretty likely that Harry's brain-draining helmet will end up getting used against The Thinker in some way. And if that's the case, then Harry's mental problems will not have been suffered in vain. If the price of removing one evil brainiac from society is the quasi-loss of one mostly virtuous brainiac, then it's hardly a price to pay at all. Not when the fate of everyone else's brainpower is at stake, thanks to DeVoe's Enlightenment plans. Perhaps accepting that aspect is the most heartbreaking point of the whole shebang.
Of course, if Harry ends up making one last attempt to use the helmet to reverse his issues, and he ends up turning into the Season 5 villain for the finale, then I'm revoking all my sympathy. All of it!
The Flash airs Tuesday nights on The CW, with Tom Cavanagh again pulling multiverse duties for "Harry and the Harrisons." That big finale is coming on May 22, too, and don't forget to head to our finale rundown to see when all the other major shows are ending. Then jump to our summer premiere schedule to see what else is on the way.