  In friendship networks, individuals have different numbers of friends, and
the closeness or intimacy between an individual and her friends is
heterogeneous. Using a statistical filtering method to identify relationships
about who depends on whom, we construct dependence networks (which are
directed) from weighted friendship networks of avatars in more than two hundred
virtual societies of a massively multiplayer online role-playing game (MMORPG).
We investigate the evolution of triadic motifs in dependence networks. Several
metrics show that the virtual societies evolved through a transient stage in
the first two to three weeks and reached a relatively stable stage. We find
that the unidirectional loop motif (${\rm{M}}_9$) is underrepresented and does
not appear, open motifs are also underrepresented, while other close motifs are
overrepresented. We also find that, for most motifs, the overall level
difference of the three avatars in the same motif is significantly lower than
average, whereas the sum of ranks is only slightly larger than average. Our
findings show that avatars' social status plays an important role in the
formation of triadic motifs.
