They often observe many mortal events, considering them as entertainment. Their large numbers and their ability to move around without attracting attention, their abilities, especially in acquiring information, are greatly underestimated by most. Harry develops a loyal group of Dew drop faeries (called the "Za Lord's Guard") in the course of the series; they follow him for a regular payment of pizza—with which they are infatuated—and for the glory and honor they accrue among other Dewdrop fae by conducting successful missions on behalf of their "Za Lord" (Dresden). They can vary in size from fly-sized, such as Elidee in "Summer Knight" to Toot-toot's fifteen inches tall as of "Changes", though Toot's size is an increase from when first seen in "Storm Front", possibly due the power he has amassed from increasing followers in the Za-lord's guard. Cobbler elves who are obsessed with shoes, crying out when Harry threatens to snap a pair of Prada stilettos in the short story "It's My Birthday Too". They seem to count as a subset of the Little Folk. The Tylwyth Teg are an independent kingdom of the wyldfae ruled by their king Gwyn ap Nudd. They are small, only a few feet tall however can take on the form of any creature, having a particular fondness for goats, but can look like any creature including human. In the short story "Curses" it is revealed that if treated well by mortals they would perform tasks for them (grooming of goats being a common one) and if respect was not shown, they could retaliate, going so far as to kill. The offspring of a fae and a mortal is called a changeling. They may have odd appearances, depending on their parentage. The offspring of a human and a troll, for example, may appear as a human which is incredibly tall and broadly built with a bulky mass and well-defined jaw. Other changelings have been shown as simply having oddly colored hair, such as green. Changelings must eventually choose whether to become a mortal or a Sidhe. Upon making the choice, the changeling becomes either completely mortal or Sidhe, no longer retaining any of the characteristics of the other half. It is unknown if there is any specific time or age at which a changeling must choose, but during times of war, they are affected by the calling to choose just as the Wyldfae are.