User blog comment:Touchinos/“Our Father, Who Aren’t in Heaven” Discussion/@comment-27669262-20191213174837/@comment-68.217.236.247-20191226130007

Lucifer may have also had mental contact with some of his top level demons. He seemed to have no trouble contacting Dagon for baby updates. Maybe he got a news update as soon as he escaped.

Don't underestimate the 10 years Michael spent with nothing to do but talk to Adam. If they are both sane, no doubt it's because they had each other. Unlike Lucifer and Sam, Adam hadn't opposed Michael, so they had a better place to start from (plus, not Lucifer). It may have been the difference that made Michael able to accept what Castiel showed him, rather than reject it the way he did Castiel's words.