Well I have 2 bettas ones name is loui and the other one ares like the god of war but ares is'nt aggressive at all which bettas should be aggressive loui see my fish he'll charge but he is stuck in his own cage so he can't get ares ares I put him in my sisters guppy tank and he didn't attack at all he just swam around doing nothing what should I do!!!
If you wanted to see him flare that bad, all you had to do was put a mirror in front of him - even then, they don't always flare (well at least mine doesn't).