Kate blames herself for Jack's death, and so far we still have basically no idea why. She told Toby last season that it's her fault he's dead, and the guilt she has is palpable, especially in the scene at fitness camp when she cries out in a fit of emotional pain. Some have theorized that she starts the house fire that may or may not be Jack's demise.

Kate keeps Jack's ashes with her at her apartment, and watches every single Pittsburgh Steelers football game with them. How was it decided that Kate gets the urn? And do the Steelers hold more significance to Kate after Jack's death? She never is outwardly seen expressing a huge interest in football in flashback scenes, although she does say that her family has always held football close to its heart. But perhaps the Steelers have something to do with the day of his death — more on that later.

Kate also told Toby that Jack was killed by a "sickness." What exactly that means is still unclear, although when she first said it we might have been lead to think that some kind of cancer or severe illness took his life. Now, we know it would make sense for her to be referring to alcoholism, which is our next clue.

We've seen a lot of Jack's struggle with alcohol — no matter how great of a father and husband he manages to be, it's still a demon that exists inside him. We've also seen that he's not afraid to drink and drive, unfortunately, which could potentially contribute to his death in some way, especially if he was racing home to a burning house.

Perhaps the biggest gut-punch to audiences during the entire run of the show so far was when Rebecca solemnly pulled her car up in front of the destroyed remains of the family's home. There was obviously a fire, and we know that it directly contributes to Jack's death. Creator Dan Fogelman said as much to Variety. "[Fans] don’t know the details. Did he die in the fire? Did he get out of the fire? But we’re not misdirecting. He didn’t die four years later."

In the first episode of the second season, before Rebecca pulls up to the ruined home, she glances over at her passenger's seat. There sits a bag of Jack's belongings — all seemingly in fine condition. Mint condition notebooks and watches aren't something you'd expect to see pulled from the body of a man who was killed in a fire, so this adds more fuel to the theory that though the fire somehow contributed to his death, Jack may not have actually perished inside the house.

Some people are still speculating that the washing machine the show focused on for a bit in the first season has something to do with the house fire. Reddit user ashelizabethmoon theorized last month that the fire is somehow started by an electrical malfunction. The user also claims that this could explain why Kate blames herself for Jack's death — Kevin's bedroom was in the basement, and in that cast it'd be hard for him to climb the steps to get out in an emergency. If Kate was covering for Kevin when he may have snuck out, and Jack died trying to save him when he wasn't even really there, that could explain Kate's misplaced guilt. It would also add a whole layer of heartbreak to think that something Jack was so excited about buying would eventually lead to his demise.

This also ties into the previous clue. Kevin has a cast the night of the fire, but notably, not at Jack's funeral. This means that some time transpired between the fire and the funeral — whether that means Jack survived for a time after the fire happened or the family just wanted to wait a bit for unknown reasons to hold a memorial service still remains to be seen. And as said above, the cast would hinder him from getting outside quickly if the washing machine caught fire, causing Jack to run inside for him even if he'd snuck out — and sneaking out to hang out with a girl seems like a very "Kevin" thing to do.

The dog Kate has after the fire is definitely something audiences have been told to pay attention to, Could Jack have run inside to save Kate's dog from the fire, leading her to believe his death was her fault?

Randall's girlfriend is another thing we've been told to pay attention to, in addition to Kate's dog and Kevin's broken leg, although so far it's the clue from that scene in the finale that remains the most unclear. "I think all of the questions that were posed around it — the broken leg, the dog, the girlfriend — all of that is interesting," Mandy Moore said, according to Entertainment Weekly. The girlfriend (who audiences have still yet to meet) seems to play some sort of part in the night of the fire, but we don't yet know exactly how.

In the Halloween episode of This Is Us, 20-somethings Kevin and Kate have a conversation about their father. "You still sitting in your car, eating fast food, staring at where the house used to be?" Kevin asked her. "Even if you sit there in the exact same spot that you were when you left, he's not coming back." This leads audiences to believe that Kate was right outside the house when Jack went inside, and helps us determine more circumstances of the fire, though it's still not clear what exactly went down.

In that heartbreaking scene that reveals the burnt house, Rebecca is wearing a Steelers shirt. Reddit user darkjet204 theorized that perhaps the family was watching the Steelers game elsewhere while Jack worked on renovating the house, and that's when the fire broke out. That could also be why Kate is so adamant about watching the games every Sunday with Jack's remains — because she wishes he would've been there for that last game.

As seen in the Nov. 28 episode, Kevin wraps up this half of the season with a DUI charge after flying down the street in his car through a screwdriver-induced haze. We've seen in the past that Jack's gotten behind the wheel while drunk more than once. Kevin's dive into substance abuse coupled with the pain he still feels surrounding Jack's death could hint at some parallel between the two, and would add another layer to the Pearson's pain if Jack was drunk when he raced home to the fire.

Jack's been reluctant to tell the truth about his time in the military, even to his wife. But in the midseason finale, we saw him take Randall to the Vietnam Veterans Memorial in Washington, D.C., supposedly visiting the name of his brother. It obviously still haunts him — could the "sickness" Kate talked about be PTSD? Or could the memories be another factor contributing to his alcoholism? Reddit user brinelull speculated that some of the music in a previous episode even sounded similar to helicopter blades, and predicted that his death will somehow revolve heavily around his time in Vietnam.

Heart palpitations from audiences across the country were in full swing during the entire Big Three trilogy of episodes, as Jack fiddled with the faulty fuse box and Rebecca lit candles everywhere. Now we know that Jack was definitely performing electrical work on the house, and that "damn fuse" is looking like it might just be the culprit that steals Jack from us once and for all...

With all these clues from just one and a half seasons, there's sure to be more when This Is Us comes back from hiatus. We're speeding towards the big reveal, and it's going to be a painful, emotional ride.