  We use fluctuating magnetic helicity to investigate the polarisation
properties of Alfv\'enic fluctuations at ion-kinetic scales in the solar wind
as a function of $\beta_p$, the ratio of proton thermal pressure to magnetic
pressure, and $\theta_{vB}$, the angle between the proton flow and local mean
magnetic field, $\mathbf{B}_0$. Using almost 15 years of \textit{Wind}
observations, we separate the contributions to helicity from fluctuations with
wave-vectors, $\textbf{k}$, quasi-parallel and oblique to $\mathbf{B}_0$,
finding that the helicity of Alfv\'enic fluctuations is consistent with
predictions from linear Vlasov theory. This result suggests that the non-linear
turbulent fluctuations at these scales share at least some polarisation
properties with Alfv\'en waves. We also investigate the dependence of proton
temperature in the $\beta_p$-$\theta_{vB}$ plane to probe for possible
signatures of turbulent dissipation, finding that it correlates with
$\theta_{vB}$. The proton temperature parallel to $\mathbf{B}_0$ is higher in
the parameter space where we measure the helicity of right-handed Alfv\'enic
fluctuations, and the temperature perpendicular to $\mathbf{B}_0$ is higher
where we measure left-handed fluctuations. This finding is inconsistent with
the general assumption that by sampling different $\theta_{vB}$ in the solar
wind we can analyse the dependence of the turbulence distribution on
$\theta_{kB}$, the angle between $\textbf{k}$ and $\mathbf{B}_0$. After ruling
out both instrumental and expansion effects, we conclude that our results
provide new evidence for the importance of local kinetic processes that depend
on $\theta_{vB}$ in determining proton temperature in the solar wind.
