Today is the feast of James, the Apostle, one of the first twelve disciples and with his brother John often called the "Sons of Thunder." The Gospel for today's Daily Office readings tells briefly of Jesus' call to these two and another set of brothers (Peter and Andrew).
It's interesting that Jesus chose to call two sets of brothers into his select twelve. We share things with a sibling that can't be matched with any other human being. We usually share a gene pool and unless separated by more than the usual number of years, a unique set of parental influences and other formative experiences. That's not to say we always get along! But we always have reason to try to get along. Their place in our lives can never be completely filled by another.
Perhaps Jesus knew that being part of his inner circle would bring hardship the likes of which none of those called had ever seen. Perhaps he wanted the bonds of brotherhood to help these disciples through the challenges ahead.
Various Christian communities routinely refer to one another as "brother" or "sister." This is true not only of religious orders, but also among some Baptists, Shakers, and Pentecostal expressions of Christianity. There is deep meaning in communicating to others that "their place in our lives can never be completely filled by another," to quote my own words above. And it underscores that we are baptized into one family.
So, dear sisters and brothers, have a great day!