Revelation 12:7-9New International Version (NIV)
7 Then war broke out in heaven. Michael and his angels fought against the dragon, and the dragon and his angels fought back. 8 But he was not strong enough, and they lost their place in heaven. 9 The great dragon was hurled down—that ancient serpent called the devil, or Satan, who leads the whole world astray. He was hurled to the earth, and his angels with him.
Any thoughts on Michael? Who is he? He seems to have a great role in things but not really mentioned much
There are only two mentions of Michael (Hebrew Mikael) the Archangel, here and in Jude 1:9. However, the fact that Michael and Gabriel are mentioned in Scripture means that they are significant to God.
Archangels are apparently the chiefest of angels, and so Michael is the one who leads the holy angels against Satan (the chiefest evil angel) and his army of evil angels. We need to be cognizant that on both sides there are countless angels, however the holy angels outnumber the evil ones. Also on both sides there are hierarchies of angels, designated as thrones, dominions, principalities, powers, rulers of the darkness of this world (for the evil ones), and spirit or spiritual wickedness in high places. We also see from Scripture that evil angels have been given authority by Satan over specific countries, and direct their affairs from behind the scenes.
The errors of some cults are (1) equating Michael with Christ, (2) making Christ the brother Satan, and (3) making Michael the Restrainer of Satan, rather than the Holy Spirit. Some may not even be aware of this but Michael has become "Saint Michael" for the Roman Catholic and Eastern Orthodox churches. However, there is no way that any angel can become a saint, since salvation is not offered to angels and the saints are the ones who have received the gift of the Holy Ghost (and have thus been sanctified).
On earth it is God alone who can restrain Satan, and that is why Jude tells us that even Michael the Archangel dared not bring "railing accusation" against the devil, but instead said "the LORD rebuke thee". At the same time the Lord empowers and delegates Michael before the Tribulation to lead the army of holy angels against Satan and his angels, and as a result they are cast down to earth. See Revelation 12.