One of the most important things for any party-based RPG to get right is that feeling of everyone having a place.
This can be handled in two different ways according to what kind of RPG we’re contemplating. Dungeon crawlers like Demon Gaze take a mechanics-focused approach in which every member of your party has an important role to play in combat, but outside dungeons they tend to fade into the background somewhat, with the player-controlled protagonist tending to take centre stage for important events.
Meanwhile, more story-centric RPGs emphasise the narrative trope of nakama, a Japanese term typically used to refer to the idea of true companionship — the idea of a group of characters who band together and become a substitute family for one another. They may not necessarily agree on everything, but they share common bonds that are usually strengthened by their shared hardships.
One of the things I liked most about the original Tales of Xillia was that it blended elements of both of these approaches. And its sequel, unsurprisingly, follows suit.