With This Is Us in its final season, much attention has been paid to that flash forward, in which the gang gathers for what appears to be Rebecca's last moments. One particularly interesting thing about that final scene — which we've seen in pieces over the last two seasons — is the presence of Toby, who, as we now know, isn't Kate's husband by the end of the series. While Kate is MIA (and possibly not even alive anymore, if a popular fan theory holds true) one fan on Reddit has a theory as to why Toby may still be around to see his former mother-in-law at the end of her life.

As fans know, Rebecca is suffering from degenerative memory loss, and is already grappling with the fact that she may one day not remember her most precious memories. Earlier this season, she spoke about wanting to know what her last memory will be. That may be what her family is doing at the cabin: Creating the perfect "final memory" for Rebecca, exactly as she wanted it before her condition worsened to the point where she was unable to plan. Beth, for example, brings the Pin the Tail on the Donkey game — something that Rebecca played with her children during childhood.

Redditor Auntiet95 writes, "In the flash forward, we see/hear Randall ask Toby if he is coming down. Toby is hesitant to go. I think his hesitancy stems from the fact that he was with Kate when the plans were made but isn’t any longer. Rebecca doesn’t know that though because of her illness. She likely still believes Kate and Toby are married. Toby and the others obviously know though, which makes Toby feel uncomfortable. Randall reassures him that 'she' would want him there."

If this theory comes true, it would mean that Rebecca never recognized her daughter's second marriage to Phillip — which is quite sad in its own way. However, there are clues that Rebecca's condition is worsening more rapidly, such as the fact that Kate and Toby no longer want her to babysit the kids without someone else supervising. Perhaps Rebecca's memory goes downhill in the next few episodes, just as Kate and Toby's marriage implodes — but instead of burdening Rebecca with news of her soon-to-end relationship, perhaps Kate just pretends everything is well and good with Toby in order to keep her mom happy.

While this theory explains Toby's presence, it also might explain Kate's absence. If Kate really does pass away between now and that last flash forward, Rebecca may never know it. Toby being by Rebecca's bed side may be a way for them to pretend like Kate is there, too — Toby can be Kate's "stand-in," and claim that she's just in the other room, all to make sure that Rebecca is happy in the final days of her life.

Of course, perhaps the explanation for Toby's presence isn't so tragic: Maybe he's included in the Pearson clan because, even though he and Kate are no longer together, he's still family. Still, I'd keep my eye out for a big twist — This Is Us has certainly pulled them before.