A Klingon ritual, known as the bonding, in which two people become brothers and their families are joined, performed by Worf with the orphaned Jeremy Aster.
R'uustai is a Klingon ceremony that makes two unrelated people kin. The participants light candles, put on ceremonial sashes and speak words honouring their mothers, after which each belongs to the other's family.
It is seen in The Bonding in 2366. Lieutenant Marla Aster, an archaeologist, is killed by an old mine during an away mission that Worf commands. Her twelve-year-old son Jeremy is left without parents, and Worf, an orphan himself, feels responsible.
An energy being from the planet tries to comfort the boy by taking his mother's shape, until the crew persuade it that he must be allowed to grieve. Worf then invites Jeremy to perform the R'uustai with him, making the boy a member of the House of Mogh.