There are a lot of worlds in which they never meet at all. Or meet once, briefly, and then never see each other again. But in every world where they meet, and stay in contact, stay aware of each other? Kankri Vantas and Porrim Maryam have each other's backs when shit gets truly serious, and will kill or die to defend each other. Even the worlds where they drive each other completely up the wall. Kankri, being Seer of Blood, knows this, and approves of it. It's one thing about his other lives that is not in the least pr96lematic.