Doppelgeist is a pair of Hunters who fight together as lifelong partners, bound together by oath, regardless of their gender. Their bond is not reflected only in their closeness and willingness to lay down their lives for one another, but also in oath—one sworn in front of the Council.
Not all Vampire Hunters are required to have doppelgeists; it is actually less common to have them. A Vampire Hunter has only eighteen years to find and choose a doppelgeist; once older than that, the ritual is no longer open to the Vampire Hunter.
Today, doppelgeist must be bonded in childhood; that is, before either has turned nineteen years old. They are not merely warriors who fight together; the oaths that newly made doppelgeist take in front of the Council include vows to lay down one's life for the other, to travel where the other travels, and indeed, to be buried in the same place.
A Vampire Hunter may choose only one doppelgeist in his/her lifetime and cannot perform the ritual more than once. Most Vampire Hunters never have any doppelgeist at all; so, being fortunate enough to find someone worthy of becoming ones' doppelgeist is considered a blessing. This ritual bond enhances the natural feelings of love and friendship that already exist between the pair; however, this does not prevent rivalry or hate from forming between them.