  We explore by theoretical means an extreme renormalisation of the eigenmodes
of a dimer of dipolar meta-atoms due to strong light-matter interactions.
Firstly, by tuning the height of an enclosing photonic cavity, we can lower the
energy level of the symmetric `bright' mode underneath that of the
anti-symmetric `dark' mode. This is possible due to the polaritonic nature of
the symmetric mode, that shares simultaneously its excitation with the cavity
and the dimer. For a heterogeneous dimer, we show that the polariton modes can
be smoothly tuned from symmetric to anti-symmetric, resulting in a variable
mode localisation from extended throughout the cavity to concentrated around
the vicinity of the dimer. In addition, we reveal a critical point where one of
the meta-atoms becomes `shrouded', with no response to a driving electric
field, and thus the field re-radiated by the dimer is only that of the other
meta-atom. We provide an exact analytical description of the system from first
principles, as well as full-wave electromagnetic simulations that show a strong
quantitative agreement with the analytical model. Our description is relevant
for any physical dimer where dipolar interactions are the dominant mechanism.
