The church of the presbyter Valerianus is not mentioned. There is some possibility that he can be identified with another Valerianus, cleric from Fermo, who in 580 was himself ransomed from captivity by Fabius, then bishop of Fermo. As a former captive, he might have felt incentive to help others still in confinement. However, it is just a speculation.
What is quite certain is that Valerianus passed through Rome on his way Barca in order to obtain the letters of recommendation from Gregory.