What is the origin of Felattio?

This marvellous and excitefull act has its story other than your bed and pleasure :)
The English noun fellatio comes from fellātus, which in Latin is the past participle of the verb fellāre, meaning to suck. In fellatio the -us is replaced by the -io; the declension stem ends in -ion-, which gives the suffix the form -ion (cf. French fellation). The -io(n) ending is used in English to create nouns from Latin adjectives and it can indicate a state or action wherein the Latin verb is being, or has been, performed.
Further English words have been created based on the same Latin root. A person who performs fellatio upon another may be termed a fellator. Because of Latin's gender based declension, this word may be restricted by some English speakers to describing a male. The equivalent female term is fellatrix.

Fellatio is also sometimes practiced when sexual intercourse can create a physical difficulty for a sex partner. For example, it may be practiced during pregnancy instead of vaginal sex by couples wishing to engage in intimate sexual activity while avoiding the difficulty of vaginal intercourse during later stages of pregnancy
In ancient Greece and modern Japan, fellatio has been referred to as "playing the flute"; the Kama Sutra has a chapter on auparishtaka (or oparishtaka), "mouth congress".
Galienus called fellatio "lesbiari" since women of the island of Lesbos were supposed to have introduced the practice of using one's lips to give sexual pleasure.
The Ancient Indian Kama Sutra, dating from the first century AD, describes oral sex,discussing fellatio in great detail and only briefly mentioning cunnilingus. However, according to the Kama Sutra, fellatio is above all a characteristic of eunuchs (or, according to other translations, of effeminate homosexuals or transwomen similar to the modern Hijra of India), who use their mouths as a substitute for female genitalia.
The author states that it is also practiced by "unchaste women" but mentions widespread traditional concerns about this being a degrading or unclean practice, with known practitioners being evaded as love partners in large parts of the country. He seems to agree with these attitudes to some extent, claiming "a wise man" should not engage in that form of intercourse while acknowledging that it can be appropriate in some unspecified cases.
The religious historian Mircea Eliade speaks of a desire to transcend old age and death and achieve a state of nirvana in the Hindu practice of Tantric yoga. In Tantric yoga the same emphasis is placed on the retention and absorption of vital liquids and Sanskrit texts describe how semen must not be emitted if the yogi is to avoid falling under the law of time and death.
In Islamic literature the only form of sex that is always explicitly prohibited within marriage is sex during menstrual cycles. But the exact attitude towards oral sex is a subject of disagreements between modern scholars of Islam. Authorities considering it "objectionable" do so because of the contact between the supposedly impure fluids emitted during intercourse and the mouth.Others emphasize there is no decisive evidence to forbid it.

The Moche culture of ancient Peru worshipped daily life including sexual acts. They depicted fellatio in their ceramics.
According to the research of Russian anthropologist S. M. Shirokogoroff, in the Manchu tribe of the Amur river mothers used to put their male babies' penises into mouths as a caress, since it was not considered a sexual act.