In the first three centuries, Christians held a variety of christologies, including subordinationist and egalitarian.
The only egalitarian theory prior to the fourth century was modalism—the Son just is the Father (held by Sabellius and others).
Nearly all Christians held to one of three subordination christologies.
The Gnostic approach saw Christ as an intermediate heavenly being who (in some schemes) came to earth to bring salvation. He appeared to be in the flesh, but this was an illusion.
The Dynamic Monarchians believed Jesus began his existence when he was miraculously conceived.
The Logos Incarnationists believed God begot the Word through whom he created the world before becoming Christ. For them, the Father is superior to the Son in origin, role, and substance.
Drawing on his neo-platonic training, Origen first developed the idea of eternal generation, enabling him to affirm both the Son’s eternality and inferiority to the Father.
Tertullian theorized that the Son derived his substance from the Father, but not the same amount.