Why Does the Game have Two Realms?

This is not a unique concept of the game. Several MMO games in the past have already featured the same thing. For instance RF online had three races that co-existed in the game, but never got to converse with other races other than when inter-race battle occurs. This is pretty much the same in Royal Blood. There isn't a benefit in picking any of the two realms as you'd generally be able to build the same class of characters while playing.

Ideally, the game picks a realm for you in order to balance the number of players in each realm. This way, it would always have the same number of active players at a time. However, if you have a particular group that wants to play with you in a particular realm, you have the option to pick among the two realms manually.

It is plausible though that later on in the updates of the game, there will be some key differences in picking each of the realms. Below are the two choices you have, and their accompanying info as provided by the game when creating your first character.

Aslan

The Aslan Realm is known to be a disciplined faction that never back down in the face of an enemy. They work towards a unified empire. The Aslan Realm looks to welcome you, an invincible guardian, to join them in the war against the Legion.

Harmion

The Harmion Realm, founded by powerful gods, shreds any threat in their path to pieces. They work towards a cooperative alliance. The Harmion Realm looks to welcome you, an ice-cold avenger, to join them in the war against the Legion.

Additional Info:

1. Realms cannot be changed once selected.

2. Restrictions may apply once one of the a particular realm is overpopulated.

3. Players from both realms only get to see each other during Realm versus Realm battles.