We pray in Psalm 133:1-2: 

How good and how pleasant it is, when brothers dwell together as one! Like fine oil on the head, running down upon the beard, upon the beard of Aaron, upon the collar of his robe. 

When the Psalm is applied to the priest, we first notice that it refers to “brothers who dwell together as one” and then compares them to “fine oil on the head” of Aaron, consecrated as God’s priest with the precious oil of anointing (Leviticus 8:12), as priests are anointed today when they are ordained. 

The priests of Christ “are united among themselves in an intimate sacramental brotherhood” and this is in “virtue of their ordination to the priesthood” (Presbyterorum Ordinis 8). The priests’ fraternity stems from their sharing the same vocation and consecration to the Lord. Pope Saint John Paul II further expresses this in his letter to all priests on the occasion of his first Holy Thursday as Pope (April 8, 1979) when he says:

With you I seek the ways of spiritual union and collaboration, because by virtue of the sacrament of Orders, which I also received from the hands of my Bishop, you are my brothers. 

For this fraternal spirit to become a reality in which priests truly would live in an atmosphere of brotherly friendship and mutual support, they must always have in the forefront of their mind and heart the sacredness of the vocation and consecration which they share. This vocation and consecration comes from the Lord himself who, like the Prophet Jeremiah, called the priest before he was born (Jeremiah 1:5) and the same Lord says to his disciples: “I have called you friends” (John 15:15). As friends of the Lord the priests are to be as friends and brothers to one another as the Lord is to them and thus calls them to be to each other. The Decree on the Ministry and Life of Priests (8) reminds us that “Each and every priest, therefore, is united with his fellow priests in a bond of charity, prayer and total cooperation.”   

This fraternity needs to begin in the seminary, when the men are preparing for the priesthood. The friendships made while in the seminary will last a lifetime, thus they must be friendships rooted in the love of Christ. 

Pope Benedict XVI reminds us of this in his Letter to Seminarians (October 18, 2010):

The seminary is a time when you learn with one another and from one another. In community life, which can at times be difficult, you should learn generosity and tolerance, not only bearing with, but also enriching one another, so that each of you will be able to contribute his own gifts to the whole, even as all serve the same Church, the same Lord. 

Pope Francis also refers to this when addressing the International Theological Symposium on the Priesthood on February 17, 2022 as he says: 

Fraternal love, provided we do not make it saccharine, redefine it or diminish it, is the “great prophecy” that we are called to embody in today’s throwaway society. “By this everyone will know that you are my disciples, if you have love for one another” (Jn 13:35). 

Thus priestly fraternity must be down to earth and deeply rooted in the seriousness and sincerity of the priestly vocation and consecration. This must be found to be mutual brotherhood among priests, not just on the part of some and not others, keeping in mind that “The priest's fundamental relationship is to Jesus Christ, head and shepherd” (Pastores Dabo Vobis 16); only then will “everyone will know that you are my disciples” (Jn 13:35).