The Scriptural teaching regarding the nature and origin of the devil and demons has been summarized by the Orthodox theologian Michael Pomazanski:
According to the testimony of the word of God, the origin of sin comes from the devil: He that committeth sin is of the devil; for the devil sinneth from the beginning (I John 3: 8). The word “devil” means “slanderer.” Bringing together the evidence of Sacred Scripture, we see that the devil is one of the rational spirits or angels who deviated into the path of evil. Possessing, like all rational creatures, the freedom which was given him for becoming perfect in the good, he “abode not in the truth” and fell away from God. The Saviour said of him: He was a murderer from the beginning, and abode not in the truth, because there is no truth in him. When he speaketh a lie, he speaketh of his own: for he is a liar and the father of it (John 8: 44). He drew the other angels after himself into the fall. In the epistles of the Apostle Jude and the Apostle Peter, we read of the angels which kept not their first estate, but left their own habitation (Jude, v. 6; compare with II Peter 2: 4).1
The Chalcedonian doctrine of the devil and demons was summarized by John of Damascus (676-749):
He who from among these angelic powers was set over the earthly realm, and into whose hands God committed the guardianship of the earth, was not made wicked in nature but was good, and made for good ends, and received from his Creator no trace whatever of evil in himself. But he did not sustain the brightness and the honour which the Creator had bestowed on him, and of his free choice was changed from what was in harmony to what was at variance with his nature, and became roused against God Who created him, and determined to rise in rebellion against Him: and he was the first to depart from good and become evil. For evil is nothing else than absence of goodness, just as darkness also is absence of light. For goodness is the light of the mind, and, similarly, evil is the darkness of the mind. Light, therefore, being the work of the Creator and being made good (for God saw all that He made, and behold they were exceeding good) produced darkness at His free-will. But along with him an innumerable host of angels subject to him were torn away and followed him and shared in his fall. Wherefore, being of the same nature as the angels, they became wicked, turning away at their own free choice from good to evil.1
Given the premise that angels became demons by their own choice at one time, did any Church Father prior to the 4th Ecumenical Council (451) or any subsequent Chalcedonian Church Father in the first millennium ever expound a belief that additional angels could also choose to become demons in the future?
1. Orthodox Dogmatic Theology (3rd ed.; St. Herman of Alaska Brotherhood, 2005), p.153
2. The Exact Exposition of the Orthodox Faith in Book II, ch.4