Cross-Fate Episodes are additional Fate Episodes that can occur between characters that have been obtained. Viewing these episodes will result in additional stats, most of the time, or skills for both characters.
Cross-Fate bonuses are not tied to individual Cross-Fate Episodes themselves, but rather it is based on how many episodes of a character the player has completed. For example, Yuel has a Cross-Fate with both Mary and Societte. The table lists Yuel's bonus as HP +270 / ATK +360, which means that the first episode you view will grant Yuel an additional 270 HP, while the second Cross-Fate will give Yuel additional 360 Attack. If you have both Mary and Societte, whether you view Mary's first or Societte's first, Yuel will gain 270 HP in either case. The viewing order does not matter.
Cross-Fate Episodes are specific to a single character version if that character has multiple versions. Yuel's Cross-Fate with Societte, Fully Blossomed, will only be available if both Yuel and Societte are owned. Yuel (Water)/Yuel (Event) and Societte (Fire) will not count.
If available, the prerequisite Fate Episodes for participating characters unlock when their first two respective Fate Episodes are cleared, regardless of rarity.