Social media channels are frequently used by different audiovisual products when promoting content and generating conversations around their brands. In the case of fiction series broadcast by Netflix, the most widely used social media are Instagram, Facebook, and Twitter. This research aims at stablishing what the characteristics are of the content that, published on the profiles of said platforms by the accounts of these fiction series, generate greater efficiency and virality. To do this, we analyze the eight publications with the highest number of total interactions in a sample of series profiles to determine which platform, formats, types of content, hashtags, emojis or appealed values, among other factors, obtain better results in terms of the different types of interaction: likes, comments, and shares. The main results point to Instagram as the most efficient social network, where images are the content with the highest number of interactions. On Facebook and Twitter, however, videos get the highest efficiency and virality. For the rest of the analysis categories, we will find differences between the three platforms.