Grandparent (rank)

According to The Book of the War, the founder of a Great House on The Homeworld was originally designated that House's grandfather, although by the time of the War, and for a long while before it, the term was archaic and went unused by the ruling Houses.

Despite this, one member of House Lungbarrow cited this protocol, as it had technically never been removed, declaring himself the Grandfather of House Paradox, using the word "paradox" because it was maxinally offensive to them. (PROSE: The Book of the War)

The Doctor was often called "grandfather" by Susan, (TV: An Unearthly Child et al.) John, and Gillian, (COMIC: The Klepton Parasites et al.) despite claiming to lack the capacity to reproduce biologically. (PROSE: Cat's Cradle: Time's Crucible)