The Housing System. You can buy houses on many of the Major cities in Arelron. On these houses, you can do things like shopping, resting, craft/dismantle items and also learn more about your characters, chatting to them on interesting conversations.
Isn't it?
It's one of the most story-centered systems I've ever planned. There are lots of things you'll know about all your characters. Also, some quests can start you you talk to one of your characters about one of his/her past events.