Exactly how steamy is this story?
PG-13
Feed rates a solid PG-13 on the steaminess scale—and maybe pushes that in at least one place.
For one, it's pretty clear that these teens are looking for some hook-up action (although this is not presented in graphic terms). There's also a sly reference to Titus trying to see through Violet's hospital gown when they're in the hospital on the moon.
And then Titus and Violet get into some pretty hot-and-heavy smooching in a couple of scenes, but when they finally get their only opportunity to seal the deal, Titus is unable to perform. Even though Violet heroically tries to remedy this problem (there are references to her fondling him, but—again—this is not presented in graphic terms), it's a no-go for Titus. He's so grossed out that Violet is likely to die soon that he more or less considers her a zombie. So, this scene is quite un-steamy, and is instead a portrait of that awkward moment when things just don't work out.
The only other glaring sexual reference comes in the form of a kids' television show (or feedcast). That's right, folks: a kids' show. So, it's pretty clear that we're way outside the realm of abstinence-only sex ed. At the dinner table, Smell Factor (Titus's little bro) is listening to a show that casually mentions two varieties of sexual contact that are probably not going to make it into a Sesame Street or Yo Gabba Gabba skit anytime soon. At least, we're not holding our breath on that. Nothing graphic, but it could raise several eyebrows, since it's mentioned in relation to young children.