Bonds between friends is one of the core themes in Final Fantasy 7: Rebirth, and plays a bigger role than ever in terms of gameplay. By building strong relationships between Cloud and the entire cast of characters, you will not only unlock powerful new moves for every pair you can perform, but also open them up as potential partners on a date in the latter part of the game.
Unlike some other games, there's no gift-giving mechanic to boost your bonds in Final Fantasy 7: Rebirth, meaning you will need to do a bit more work to build up that trust. Cloud may seem like a loner, but you can help him become friends with all his companions by following these methods.
How to increase character bonds
You can see how each party member views Cloud when exploring various towns during the story based on a little emoji above their heads. The happier it looks, the stronger your bond with them is. While they will all start out at the bottom, there are more than enough ways to boost them all to the highest level.
Step 1: The method that appears to have the greatest impact on a character's bond is side quests. Each side quest will involve one of your party members as a focus, and by completing that side quest, you will improve your relationship with said character. You won't know which quest is tied to which character until you begin, but will know upon viewing the introductory scene.
Step 2: When your party is out idling around a town at a point where you can see their bond levels, talk to them. You will get one opportunity to respond or comment on what they say, and by choosing the answer you think that character will like, get more or less of a boost to their bond.
Step 3: Finally, whenever you unlock a Synergy Attack with a character, you earn a boost to your bond with them the first time you use it in combat.