From SuspireWiki

Like all members of the First Estate, a ghoul must swear an oath not only to her regnant, but to all the Invictus. The oath, called the Oath of Villein, refers to a type of village-born serf from medieval feudalism. The villein was a bondsman, bound to the land and the lord that owned the land. He had no rights save that to live. That is, his lord could not kill him without reason and propriety. A villein's assets were his lord's assets. This oath invokes much of this same principle and carries it over to thralls. The oath itself is generally public, done before someone of local importance within the covenant such as Primogen, Priscus or Sheriff. (Rarely does a Prince concede his time for such a paltry oath.)

Truthfully, the physical act of the oath itself changes from city to city, though most would have the ghoul believe it remains static and has since the Middle Ages. Generally, a draught of blood is taken from the thrall's wrist, and those present all sample his Vitae. The ghoul swears fealty to his lord and to the First Estate. From there, he is meant to take his third and presumably final drink before the bond is fully established, though typically, this act is now more cosmetic. Generally, the regnant secures the final bond before the oath takes place, in an effort to save herself any potential embarrassment.

Example Swearing

{Oath maker's part to Oath Acceptor}

I [oath maker's full name] take knee before [oath acceptor's full name] to accept the mantle of subserviance before all of my superiors who have gathered to witness, so there may be no question as to my loyalty and my duty. I acknowledge the miraculous abilities that now flows through my veins as comming from the power of my [Master/Mistress]. Thus do I pledge now sinew, soul, and sense in service to my [Master/Mistress] from now to untill I am released, either by the embrace or by death whichever fate my [Master/Mistress] deems is to be mine.

The oath maker offers [his/her] wrist to the oath acceptor

{Oath Acceptor's part}

I [oath acceptor's full name] do accept [oath maker's full name] in [his/her] pledge and service of body, deed, and heart to myself. Also do I accept the burden of responsibility placed upon me. I acknowledge that as [oath maker's name] is bound to me by the ties of vitae, I too am bound to [him/her]. I am bound to protect, tutor, provide, and care for [him/her]. I am responsible for [him/her] before the eyes of my peers as [he/she] is mine, and as such [his/her] actions shall be considered as my own before my peers. I am bound to not waste [him/her] on whim, nor cruelty for such would be a waste and a grevious breach of the trust placed upon me by [him/her]. I accept all of these with no reservations.

The oath acceptor bites the wrist and drinks a little bit of the oath maker's blood. The oath acceptor does not lick the wound

{Oath maker's part to the Invictus}

I [oath maker's name] now acknowledge the role and power of the unconquerable Invictus, that which my [Master/Mistress] belongs to and to which [he/she] holds allegance. My [Master's/Mistress'] duties and responsibilities beholden to the covenant of rulers are now also my own. The Invictus must be respected. The Invictus preserve order and embody power. The Invictus provide, and we must provide in return to the Invictus.

The wounded wrist is offered to the Invictus

{Invictus witnesses reply}

[I/We] of the First Estate, that which has endured since before the fall of Rome, do observe and accept this oath and it's binding which makes this kine an extension of [oath acceptor's name] and acknowledge the legality, and solemnity of such a pledge and extend forth to them the protection, and privilages due to one of their station amongst us.

The Invictus drink from the wound

{Oath maker's final part}

As I have taken their vitae within me and it has become a part of me, I know that they are a part of me, and as such I am their's. Inextricably linked to my [Master/Mistress] [oath acceptor's full name], and the unconquirable Invictus. This I do swear upon the [day] of [month], [year].

The oath acceptor then bites/cuts [his/her] own wrist and offers it to the oath maker. The oath maker drinks the vitae, taking the ceremonial if not accual third drought. As the oath maker drinks, the oath acceptor licks the wrist wound inflicted close