Kafan and Beelzebub went through the same process as Roan and Beelzebub did in the past, branding their souls with the pact. With that, Kafan would be forced to go out and command everyone to leave Beelzebub alone AS LONG as Beelzebub truly helped with the war against Garisan.
Another part of the agreement was that Beelzebub should never mention about the Fragments the twins have acquired. After all, he is one of the few who knew about the twins' Fragments acquired in the past. He didn't know them all, but he was certain there were at least a few.
Kafan wasn't worried about this pact, though. Their Universe definitely needs as many experts as possible. And, if Beelzebub can really use the Semi-Celestial Dead Souls to reach the Semi-Celestial Level, then it will be another boost to their Lisan Universe.