So far, due to some unfortunate circumstances, there were two instances where my bettas met.
Bubs met Squirt when he wiggled through the divider. Entering into Squirt's territory led to some flaring, but then there was absolutely no aggression. They even swam together at times.
The second tieme was yesterday when Jingles got through the divider and found Starburst. There was some chasing, but Starburst stayed away from Jingles, hiding in the corner.
I feel like all of my fish are semi non-aggressive but then there is Jingles...
So thankful no one gets hurt :/