[@sakurasan] Humu, he is cool. I like it as it is now. Will copy and paste it to a wordpad. 

[@Zelosse] Like what Vocab said, but well, all people seal contracts in different ways. 

You can do it through Runes if your mage character uses runes to begin with, or you can prove the existance of the contract with any other kind of thing. 

Then follows the oath and vows. The oath is usually said by the magician, and the familiar repeats word by word, if they can talk, otherwise they just need to listen. Lastly, the familiar will say his vow, words of power that will determine what kind of magic they will have. They usually just come to mind in the moment.