[quote=Rin]
>.> <.<A RIVAL APPEARS
[/quote]Oh, I forgot that your civilization is also quite warlike.
Yeah, you're free to attack the Empire whenever if you don't fear a retort.
If you want you can also involve in your civilization profile that your race is constantly at war with them.

On the other hand please don't make your race too powerful for some misaligned motivation to "be the best" or "win" this game.
These kind of RPs are never about that.
Personally I think it's better to have the largest civilizations to be outside of the player's control.