You can search on popular fanfiction websites by using relevant keywords like 'How to Train Your Dragon', 'Hiccup hurt' and browse through the results.
You could try social media platforms too. Many fans share and discuss their favorite fanfictions there. Just search for groups or hashtags related to How to Train Your Dragon and Hiccup hurt fanfiction. Another option is to check out blogs or websites of passionate fans who might have curated collections of such stories.