2020-11-10 : If both creatures are controlled by the same player as Run Away Together tries to resolve, both targets are illegal. The spell doesn't resolve.

2020-11-10 : If one of the two target creatures becomes an illegal target, Run Away Together can still determine its controller only to check whether the other creature is a legal target. If the illegal target has left the battlefield, use its last known information. If the other creature is still a legal target, it's returned to its owner's hand.