Answer:
The death of Hector.
Step-by-step explanation:
Priam, being Hector's father wanted his son's body for a proper burial. Achilles enraged that Hector killed Patroclus (which is mostly taken as Achilles and Patroclus were lovers), dragged Hector's body behind on his chariot. Priam asked for his son's body and Achilles agreed to meet up at a tent. The meeting was respectful for both parties so that would be the bond between them.