The very first words we here from Syd, who is running down a street caked in blood:
Syd: Dear diary—go fuck yourself.
Stanley insists upon rolling down his car window every single time he sees somebody. It is incredibly slow.
Liam: What's he doing?
Syd: Just give him a second.
Liam overhears Syd and Dina talking about her first time having sex, though he doesn't quite catch the 'sex' part.
Liam: So, where is Stan going?
Syd: What do you mean, Goob?
Liam: Well, I overheard you and Dina talking, and you said Stanley went down somewhere. But where?
Syd hurriedly tries to claim that Stanley went down to Mexico, just as Stanley pulls up next to them.
Stanley's version of researching Syd's powers is to read a bunch of comics he thinks are relevant, concluding that they must have been based on reality.
In the same episode, Stan and Syd have an argument after Stan forces Syd's powers to come out by angering her. When she leaves, Stan angrily destroys the tower of beer cans they'd initially been using to test Syd's powers. There's a Beat, then:
Stan: Oh. Now I have to clean this up. (resigned sigh)
When having to convince Dina on why they need the library footage, Syd panics and blurts out the first thing she can think of:
Stan: Yep. It was right there in the library. We sixty-nined and everything.
This predictably falls apart when Dina sees what the library looks like and decides it's unlikely that Syd and Stan having sex caused every single bookshelf to fall down.
After Brad, Dina, and Syd are given detention, the teacher rhetorically asks if anyone else wants to join them. Stan jumps up out of his seat. There's a beat, and then he shoves his books onto the floor. Another awkward pause, and Stan follows it up with a stuttery "...m-motherfucker" just to make sure.
Afterwards, when their teacher has given him detention as well, he turns to Syd with the biggest grin on his face, and gives her a thumbs-up.
Upon learning that her dad may have also had powers like her, losing her diary, having Liam turn against her, and distancing herself from Dina and Stan, Syd has one solution in the finale: make pancakes.
Titlecard: I am okay with this.
Meta:
According to an interview with Seventeen, Richard Ellis only learned about how his character died when talking to Kathleen Rose Perkins.
Kathleen: How do you feel about your head blowing up?
Richard: What?
From the same interview:
Sofia Bryant: Dina doesn't know anything about Syd's powers. I've actually thought about this, you know, what happens after this for Dina? She's going to need so much therapy! She walks up to Brad's body and then crouches down and stares at it. Like, what are you doing? I don't even know what's next for her. I don't know what I would do in that situation because that doesn't happen every day-
