The Apostle Jude, in his own Epistle, gives himself the title: "brother of James", which is the meaning of the name Thaddeus (or Lebbeus) by which Jude was also known. In the opinion of Catholic scriptural scholars, St Jude was the full brother of St James the Less who was regarded as Christ's first cousin. On this reckoning, then, St Jude too would be counted a first cousin of Our Lord. (See St Simon)
The New Testament lists Jude as an Apostle but tells us little else about him. It does, however, record a question which he put to Jesus just after the Last Supper when Our Lord promised to manifest Himself to those who heard Him. St Jude anted to know why he would not manifest Himself to the whole world. Jesus replied: "If anyone love me, he will keep my word, and my father will love him and we will come to him and make our abode with him." (John, 14.22-13) In other words, we must merit the visit and manifestation of the father and Son by proving our practical love for them.
A Western tradition which is recognized in the Roman liturgy tells us that St Jude exercised his apostolic ministry in Mesopotamia, then joined St Simon in Persia, where they preached together, made many conversions and were martyred. Eusebius quotes a story about two grandsons of St Jude who were questioned by the Emperor Domitian who was alarmed by the report that they were of the royal house of David. Seeing them to be poor men who sought a kingdom not of this world, Domitian let them go. in our own day, St Jude is perhaps most popularly known as the patron of "desperate cases".