The Many Worlds hold a great many strange and dangerous creatures. Usually, encounters with such beings ends in bloodshed, whether it be theirs or yours. However, every now and then one of these entities reaches out and bonds with a member of the mortal species. The familiar becomes some kind of trinket that the bondmate wears, channeling the power of the familiar for their own protection.
A man wandering the swamps of Attergate encounters a will’o’wisp that glows a soft green and becomes a brooch for the man to wear.
A woman braving the deserts of Ogalt happens across a golem standing on a lonely dune. It holds out its hand to give her an amulet and she feels the golem’s energies flow through the trinket. When she puts it on, the golem is gone.
A person wakes from a terrible dream to find a Skitterling hiding under their bed. It weaves a bracelet out of its own flesh that allows the person to keep their enemies at bay. There is no Skitterling left when it is done with its craft.
Sometimes, the binding can go further. Familiars can actually infuse themselves into their bondmate taking what was once two discrete entities and making them one. This bonding is as permanent as the two wish it to be, the familiar can exist either as a trinket as previous described or as an infused part of their bondmate.
Nobody really knows exactly why bonding happens. Scholars of the Concordia Illuminata have a thousand different plausible explanations but none have been proven out. The binding of a familiar is a uncommon gift that remains a mystery to even the most educated.