Optimally doped manganite ${[\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{MnO}}_{3}$ (LSMO)] is a ferromagnetic material with perspective use in applications due to colossal magnetoresistance and ${T}_{c}$ around room temperature. However, utilizing LSMO in thin-film form and complex heterostructures is limited due to the appearance of a magnetic dead layer, but interfacing LSMO with other transition metal oxides (TMOs) can reduce the magnetic dead layer. For instance, the LSMO layer in proximity to ${\mathrm{SrRuO}}_{3}$ (SRO) remains magnetic down to 1--2 u.c. To illuminate this effect, we study the magnetic properties and orbital anisotropy of ultrathin LSMO deposited on ${\mathrm{SrTiO}}_{3}$ (STO) compared with and without an SRO intermediate layer by resonant x-ray spectroscopy. We found that two events occur at the LSMO-SRO interface: Orbital rearrangement and charge transfer. Both effects cooperate, enhancing in-plane double exchange in ultrathin LSMO. Based on quantitative analysis and theoretical simulation of the x-ray spectra, magnetic stability mechanisms in LSMO/SRO are discussed in detail.