It has Jack-on-Hiccup in it. SURPRISE!!!
- Hiccup is never portrayed as being interested in men in-canon, instead crushing on and pursuing a relationship with Astrid. Here, it is mentioned that he knew he was bisexual since he was young, and when he realizes his feelings for Jack, he turns down Astrid's offer to pursue a relationship. Jack's sexuality is never given in-canon, but here he is bisexual.
- Full-on Gayngst from Chapters 9 till 16.
- Hiccup and Jack reveals their relationship to all of Hogwarts in Chapter 21 to mixed opinions. They again reveal their relationship to Hiccup's tribe as a show of trust to his people on the day he becomes chief in Chapter 25. This is almost a mistake, given the tribe's more bigoted opinions of LGBT people, but Astrid and Fishlegs were able to point out that his orientation does not matter, causing the tribe to ponder whether or not they should fuss about it.
- Gobber admits his own sexual orientation to Hiccup as a show of comfort, admitting that while his reaction was not good at first, Stoick eventually realized that it did not matter and went on to be his friend for the rest of his life.
- Sex in chapters 20, 21 and 22.