So, much like Pokemon, each Persona you collect has its own stat line and attacks it can learn. Some of these attacks are better than others because they can do more damage or provide a good buff when used. Eventually, though, the enemies will get to a higher level than the Persona's you're using so you're expected to fuse two persona's into a higher level one with better stats to keep up with the enemy. You can also carry over those good attacks you've collected and put them on the new Persona. Each Persona is tied to a specific arcana, like The Hermit, or The Fool. Those same arcana have a social link tied to them that you can level by hanging out with the person it's attached to, like your classmate in school. By leveling the social link the Persona you fuse will get a big exp boost allowing it to gain lots of levels right away and be more powerful. Hope that cleared things up a bit.

@@RooksGamingCornerthanks so much! That clears up a lot of my confusion and was extremely helpful. Thanks!!