in SWTOR they made an interesting thing for our characters there: the option to make them relatives. There is like a social-tree where you can place each of your chars in the screen. In this way, one could be the father/mother of the other, or brothers, or whatever. You can ropleplay them based on this and it's a nice incentive for RP there.

In the same game, as someone already told, we share the same inventory (bank) with all our chars in the same server. And a lot of achievments comes from the "Legacy" system (all things you open in this system is valid for all chars in the same server like mounts, boosts, outfits, etc). It's similar to the Veteran Rewards here in XIV, but far better for alt lovers.

The alts here could receive more love, as well as RP, so... it would be cool if we have something similar to these here, don't you think?