Originally Posted by
Belhi
We did have one encounter mentioned where Leviathan and Titan were summoned at the same time and were on a collision course once during the Main Scenario but it says that the Company of Heroes took down both. It's not really clear what the two primals would do if they ran into each other. We really haven't seen battles between primals much if at all.
I could see the two groups coming to blows but I think it more likely that their differing interests would lead to them just avoiding each other. They don't have any particularly compelling reason to hate each other.