The Hunt is On

As you know, when an enemy Rengar and an Enemy Kha'Zix are on opposing teams, the begin "The Hunt is On" However, this can only occur if they are on opposite teams.

My suggestion is to create a goal for the both of them if they're on an ally team, such as first one to get drag, or, score 5 champion kills. Something along those lines to keep the interaction alive.