1. linguistic typology

Catholic clerics, among Catholic clergy, "Mr." is the correct title and form of address for seminarians and other students for the priesthood and was once the proper title for all secular and parish priests, the use of the title "Father" being reserved to religious clergy only. The use of the title "Father" for parish clergy became customary around the 1820s.
A diocesan seminarian is correctly addressed as "Mr.", and once ordained a transitional deacon, is addressed in formal correspondence (though rarely in conversation) as the Reverend Mister (or "Rev. Mr."). In clerical religious (those primarily made up of priests), Mr. is the title given to scholastics. For instance, in the Jesuits, a man preparing for priesthood who has completed the novitiate but who is not yet ordained is properly, "Mr. John Smith, SJ" and is addressed verbally as "Mister Smith"– this is to distinguish him from Jesuit brothers, and priests. (Although, before the 1820s, many Jesuit priests were also called "Mr.".) Orders founded before the 16th century do not, as a rule, follow this practice: a Franciscan or Dominican, for instance, becomes a friar after novitiate and so is properly titled "Brother" or, if a cleric, "Father".
Permanent deacons in the United States are styled as "Deacon" or "the
Reverend Deacon" followed by their first and last names (e.g., "Deacon John Jones", rather than "the Reverend Mr."). It is also customary in some places, especially in the Eastern Catholic Churches to address deacons while speaking, like presbyters, as "Father" or "Father Deacon".
"Mister" can also be used in combination with another word to refer to someone who is regarded as the personification of, or master of, a particular field or subject, especially in the fields of popular entertainment and sports, as Gordie Howe is referred to as "Mr. Hockey" or Reggie Jackson is known as "Mr. October."
Sir is an honorific address used in a number of situations in many anglophone cultures. The term can be used as a formal prefix, especially in the Commonwealth, for males who have been given certain honors or titles (such as knights and baronets), where usage is strictly governed by law and custom. It may also be used informally towards a male of superior rank or status, such as an educator, or as a form of address from a merchant to a customer [31, 84]. Equivalent terms of address to females are "ma'am" or "madam" in most cases or in the case of a very young woman, girl, or unmarried woman who prefers to be addressed as such, "miss". The equivalent term for a knighted woman or baronetess is Dame or «Lady for the wife of a knight or baronet.
"Sir" derives from the Middle French honorific title sire. Sire developed alongside the word seigneur, also used to refer to a feudal lord. Both derived from the Vulgar Latin senior, sire comes from the oblique case declension senior and seigneur, the nominative case declension Seniōrem.
The form "sir" is first documented in England in 1297, as title of honor of a knight or baronet, being a variant of sire, which was already used in English since at least c.1205 as a title placed before a name and denoting knighthood, and to address the (male) Sovereign since c.1225, with additional general senses of "father, male parent" is from c.1250 and "important elderly man" from 1362.