Imam Hassan Askari (PBUH) considers his followers to be his close family, and says, “There is a close family relationship between you and us.” This means that we are like close family members; like father and child, like brothers. A believer is the brother of another believer. That is, the relationship between two believers is that of brotherhood, as in having the same parents, not even like half-brothers. What is meant by a believer? The person who follows the way of Imam Hassan Askari (PBUH). This is the strong organizational relationship between the Imam (PBUH) and his followers.
Imam Khamenei's statements at the meeting of the “Ansar al-Hussain” in 1972; from the book "Hussain’s (PBUH) Comrades.