Bede

One son of Ahimelech escaped, Abiathar, etc. Just as Doeg the Edomite, one who struck down the priests, symbolized the sword of all executioners, so Abiathar, the one who escaped the sword of the striker, represents all the confessors of Christ who could survive that most severe persecution. Therefore, Abiathar is rightly interpreted as "superfluous father," signifying those who, glorious in the paternal title in the Church, survived such a turmoil. …

Commentary on Samuel ↗