WARNING: The following contains spoilers for I Know This Much Is True, airing Sundays on HBO.
HBO's I Know This Much Is True takes place in Connecticut in the early '90s and focuses on the Birdsey twins, Dominick and Thomas, both played by Mark Ruffalo. The twins are inextricably linked throughout their lives, but the relationship is by no means easy, especially since Thomas is a paranoid schizophrenic. The story also jumps to the past to show the twins growing up in a strained household with a neglectful stepdad, Ray, and a depressed mom, Concettina.
What really makes Ruffalo's duel performances in the series stand out, however, is that while the actor is most well-known for his role in the Marvel Cinematic Universe as Dr. Bruce Banner, it's playing twins that are two tragic sides of the same coin that actually gives him his most heartbreaking Hulk.
In the MCU, Ruffalo has cleverly brought Hulk to life as the alter-ego of Banner. By the time Ruffalo entered the franchise, the character had learned to control the beast a bit more, which has led to the emotional Hulk in Avengers: Age of Ultron, the badass Hulk in Thor: Ragnarok and Professor Hulk in Avengers: Endgame.
But I Know This Much Is True showcases a different kind of Hulk as Dom becomes the caretaker for Thomas at every turn. Thomas can't be separated from his identical twin and it has hurt them at college and even in Dom's love life. Thomas' fragile mental state is obvious right at the start of the series when he amputates his arm in a public library because he believes he's an agent of God. Voices in his head told him his sacrifice would be an offering against war and would bring peace to an unstable America.
As the story progresses, Dom has to shadow Thomas to control his public outbursts as Thomas is political, religious (and constantly quoting scripture) and his tolerance for the average Joe is near zero. It's a terrible combination that places an undue burden on Dom. Then, after Dom marries Dessa and their daughter dies from SIDs, his brother makes the situation even worse by telling telling people the FBI killed his niece because the organization thinks he's an insurrectionist.
The twins rage back and forth the same way Ruffalo portrays the Jekyll and Hyde inner-turmoil of his Hulk. In this case, though, Thomas is the rebel and chaos-bringer -- a separate body who constantly reminds Dom no matter how much he tries to run, they are one. It doesn't matter if it's Thomas threateningly scraping the kitchen table with a knife as a teen or running across the freeway into a lake, Dom thinks the fact Thomas is a walking, talking time bomb makes him one too.
This kills Dom's dreams. He has to drop out of school to babysit. He eventually becomes a house painter and when his marriage crumbles, he turns into a manic depressive drunk who only has Thomas. The twins' mom dies and their stepdad's old and unreliable, so Dom just can't cut free from his Hulk. He's been conditioned to be Thomas' crutch and support system, which is admittedly respectable and endearing. Still, as sentimental as it is, it's a burden that traps Dom in a metaphorical prison with Thomas. This is illustrated in stark detail when the decision to reattach Thomas' hand is handed to Dom, with Thomas begging Dom not to agree and others feeling Dom should consent for Thomas' own good.
Dom accedes to Thomas' wishes but this leads to Thomas being transferred to Hatch, a rundown mental facility where he won't be able to heal properly, mentally or physically. He gets more violent without his brother's supervision, fighting orderlies, smoking and simply breaking down as if he's given up. It's what Dom feared. Yet, just like Bruce Banner sometimes wishes, Dom thinks maybe if Thomas disappears, he might finally get to live his life.
Starring Mark Ruffalo, Melissa Leo, Imogen Poots, John Procaccino, Archie Panjabi, Rosie O’Donnell, Rob Huebel, Philip Ettinger, Aisling Franciosi, Michael Greyeyes, Marcello Fonte, Juliette Lewis and Kathryn Hahn, I Know This Much Is True airs Sundays on HBO at 9 p.m. ET/PT.