Later Fathers had said the Spirit eternally rests upon Christ. While even pre-Augustinian Western Fathers did mention something like a double procession (eg. Sts Ambrose and Hilary), they did not make much of it and any discussion per a hard filioque doctrine was muted. Likewise, Eastern Fathers did not go out of their way to refute double procession views, aside from mentioning the Spirit proceeded from the Father.
John of Damascene, whose views can be taken as representative of the later Eastern Fathers, and whom Thomas Aquinas relies upon heavily, argues in such a way that appears to suggest something like the Filioique, yet at the last moment completely rules it out.
Following St Gregory of Nyssa, John says the Spirit is by the Son…coming to rest upon the Son eternally. Western apologists would say that this proves that John taught the Spirit proceeded eternally from the Son. Yet, as David Bradshaw points out, if the Spirit proceeds eternally to the Son he cannot simultaneously proceed eternally from the Son (Bradshaw, 217).
Damascene’s words, therefore, refer to the eternal manifestation of the Spirit by the Son. This is similar to Gregory II of Cyprus’ analogy of the ray and the sun. Radiance exists through the ray but has its direct existence from the Son. Therefore, the Spirit and the Son cannot be thought of apart from each other, yet both have their existence from the Father alone.