  We develop a new interpretation of quantum theory by combining insights from
extended Wigner's friend scenarios and quantum causal modelling. In this
interpretation, which synthesizes ideas from relational quantum mechanics and
consistent histories, events obtain relative to a set of systems, and
correspond to projectors that are picked out by causal structure. We articulate
these ideas using a precise mathematical formalism. Using this formalism, we
show through specific examples and general constructions how quantum phenomena
can be modelled and paradoxes avoided; how different scenarios may be
classified and the framework of quantum causal models extended; and how one can
approach decoherence and emergent classicality without relying on quantum
states.
