Looking for who started it
Reconstructing the timeline is a trap: it always produces an earlier incident, and you end up in last year’s history that nobody can verify. The past is not your subject. How these two work together for the next six months is.
Putting them in a room too early
Bringing both together before you have seen them separately produces an audience, not a mediation. Each performs for you. The preliminary conversations are not a courtesy: they let you arrive knowing what is actually negotiable.
Carrying messages between them
Becoming the relay relieves everyone in the short term and entrenches the conflict: the more you pass along, the less they need each other. After a few days, refuse that role out loud.
Reducing it to a personality clash
«They’re just very different» closes the subject without touching it. Behind most durable interpersonal conflicts sits a blurred boundary, a scarce resource or unevenly distributed credit — an organisational problem that belongs to you.
Stopping at the handshake
The end-of-meeting reconciliation does not survive the next disagreement if nothing was written down. Without precise commitments and a dated review, you will be back here in three weeks with less credibility than you started with.