Season 2 of The Last of Us has been must-watch TV with a lot of amazing moments. However, the fourth episode has been the best of the season so far. The addition of Jeffrey Wright as Isaac was a big part of that. His unparalleled acting, on top of the creative team’s work, made this an intense story. Besides the Washington Liberation Front (or WLF) and one of their ruthless leaders was the storyline with Ellie and Dina as their journey hits their first big and deadly obstacle.
*** WARNING! SPOILERS FOR HBO’s THE LAST OF US SEASON 2 EPISODE 4! ***
Ellie and Dina’s trek to kill Abby brought them to a former news station inhabited by the WLF. This resulted in them almost getting caught and killed by the WLF and eventually escaping into a Seattle subway station. As predicted, that tunnel was full of the infected. If you’re a fan of the game, you know that this is where Dina thinks she has to kill Ellie because she’s infected by spores. Since there aren’t spores in the show, Ellie is bitten.
When things calmed down and Dina believes that Ellie is immune, Dina revealed that she’s pregnant with Jesse’s child. After that, the pair confirmed their feelings for each other and officially started dating (if you can call chasing a murderer in an apocalypse dating). Ellie even said that she can't wait to be a father with her and Jesse.
If you thought this happiness would last longer than a few hours, you haven’t been watching the show. Their joy is interrupted by an explosion from a distance, but they don’t know who or what caused it. If you’ve played The Last of Us Part II, you'll know what comes next.

Are two characters joining the party?
In the source material, Ellie continues looking for Abby, but leaves Dina behind because she’s pregnant. You can assume that the same thing would happen here. Nevertheless, the creative team has changed major parts of the story. They could do the same thing here. The one part that shouldn’t be altered, however, is the arrival of Jesse.
Considering that anything from the game can change for the HBO program, I’m taking a chance at guessing that Jesse is on his way. The reason for this is that his storyline is crucial to something that could happen in the season finale. Without him, the ending doesn’t have the jaw-dropping cliffhanger from the game leading to Abby’s return.
In The Last of Us Part II (Potential SPOILER Alert), Jesse ends up saving Ellie, and Tommy is the one blowing things up from afar. Even knowing this, the ending didn’t have the same “edge of your seat” feeling that the others did. There was an explosion, and curiosity about who caused it, but not much else. Thankfully, that isn't a bad thing. With everything else that happened in episode 4, having a simple ending is perfectly fine.