Michael's breathing was shallow. He was clearly in pain and might be still panicking a little from the unprovoked attack. Lucifer being here put his mind at ease somewhat but everything was just a blur. It did confuse him though - they seemed to know each other.
Leviathan does not see the difference between the General and the Archangel. He somewhat understands what Lucifer is saying but he isn't comfortable with this Michael walking around the Lightbringer's home.
"He will not survive the night. His condition may be righted if he is resurrected."