The latest episode of The Last of Us, HBO's runaway smash-hit series, may not have been quite as emotionally hard-hitting as last week's feature-length production, but it did bring to the table something equally important from the games as Bill and Frank's back-story, and that is Ellie's joke book. Discovering it - as well as a slightly more risqué piece of reading material - after their soujourn to Bill and Frank's home, Ellie attempts to lighten the mood by asking Joel a series of questions like 'what clothes do mermaids wear to math class?' and 'why did the scarecrow get an award?'

A beloved feature of the original game, 'No Pun Intended: Volume Too' may seem arbitrary to first-time viewers of the show, but it's actually a critical plot device within the structure of the game and is key to softening the relationship between Joel and Ellie, as well as establishing Ellie's innocence in a world that is anything but that.

Speaking to The Last of Us Podcast, showrunner Craig Mazin explained why it was so important to him and to his partner Neil Druckmann that the book be included:

I loved it. I remember in the game, being shocked that the game was suddenly offering me this thing that had no benefit for the game, at all. That’s what I loved about it, that it was just gratuitous but lovely and human, it was saying ‘you don’t need eyes on the back of your head, get ready to run or shoot at any moment’ but that you can take the time to stop, look around, experience the beauty of the world that had been created.

Why I thought it was essential to include in the show was that it undercuts this thing that happens when adults write kids, they either write them too young or too old. There’s this stage of like, my friend Scott Frank had the best description of this ever, and I experienced this about my kids as they were going through that age. He said “I call that time of life ‘fuck you, tuck me in’. They’re ready to go out on their own, they want to be in charge, they want a gun, they think they know everything but also, they’re still just children.

I love how Ellie has this joy for something so juvenile and stupid, and she knows it’s stupid but she loves it and it’s honest joy, and I always connect to characters showing me what they love. Pedro’s reaction is amazing, but what Neil and I agreed on when discussing its inclusion, it’s not just something that emerges dynamically and goes away when you’re pausing the game, we thought ‘what can we do with this joke book that comments on their relationship as it changes?’

Bella Ramsey as Ellie in the HBO series 'The Last of Us'
Image via HBO

RELATED: 'The Last of Us' Episode 4 Recap: We'll Get Through This“In her backpack, she has a pun book and a gun. It’s so ‘fuck you, tuck me in’. You can see their relationship organically connecting more with each other, they’ve been trying before now, but because of the joke book it’s just happening," continued Mazin. "Joel has been speaking for three episodes, but now, he’s talking to Ellie. She asks him about Tommy, and he talks for a really long time, and I loved that notion that Joel doesn’t even realise that it’s happening despite himself.”

The Last of Us stars Pedro Pascal and Bella Ramsey, and airs Sunday nights on HBO - although this weekend, the episode will be available from Friday onwards via HBO Max.