  Since the current LHC Higgs data suggest the couplings of the observed 125
GeV Higgs boson to be close to the Standard Model (SM) expectations, any
extended Higgs sector must lead to the so-called SM alignment limit, where one
of the Higgs bosons behaves exactly like that of the SM. In the context of the
Two Higgs Doublet Model (2HDM), this alignment is often associated with either
decoupling of the heavy Higgs sector or accidental cancellations in the 2HDM
potential. We present a novel symmetry justification for 'natural' alignment
without necessarily decoupling or fine-tuning. We show that there exist only
three different symmetry realizations of the natural alignment scenario in
2HDM. We analyze new collider signals for the heavy Higgs sector in the natural
alignment limit, which dominantly lead to third-generation quarks in the final
state and can serve as a useful observational tool during the Run-II phase of
the LHC.
