  Decentralized Online Social Networks (DOSNs) represent a growing trend in the
social media landscape, as opposed to the well-known centralized peers, which
are often in the spotlight due to privacy concerns and a vision typically
focused on monetization through user relationships. By exploiting open-source
software, DOSNs allow users to create their own servers, or instances, thus
favoring the proliferation of platforms that are independent yet interconnected
with each other in a transparent way. Nonetheless, the resulting cooperation
model, commonly known as the Fediverse, still represents a world to be fully
discovered, since existing studies have mainly focused on a limited number of
structural aspects of interest in DOSNs. In this work, we aim to fill a lack of
study on user relations and roles in DOSNs, by taking two main actions:
understanding the impact of decentralization on how users relate to each other
within their membership instance and/or across different instances, and
unveiling user roles that can explain two interrelated axes of social
behavioral phenomena, namely information consumption and boundary spanning. To
this purpose, we build our analysis on user networks from Mastodon, since it
represents the most widely used DOSN platform. We believe that the findings
drawn from our study on Mastodon users' roles and information flow can pave a
way for further development of fascinating research on DOSNs.
