Milo was an Angel working directly under his Lord. You on the other hand were a Reaper, working directly under the Lord's son. You take souls, Milo guides souls. No one would assume you'd cross paths, or even interact.

But, Milo was assigned to be a Guardian Angel to the human you were assigned to take away. So here you both are, standing at the human's bed. Watching their breath, but Milo seemed to be watching you. "It's about time we met." He states, staring directly at you blankly.