Obliquity excitation as a function of perturber semi-major axis, showing various initial inclinations, as labeled. The planet and perturber masses are m1 = mp = 1MJ , and the initial stellar spin period is P?;0 = 3 days. The left panels show results for an inner planet with a1 = 0:05 AU (a canonical HJ), and the right panels show an inner planet with a1 = 0:2 AU (a canonical WJ). The top panels show the nal range of obliquities (between min and max) at 4.5-5 Gyr, and the bottom panels show the nal mutual inclination variation at 4.5-5 Gyr. To excite substantial spin-orbit misalignment, an initial inclination I0 & 20 is needed, and the perturber must be located suciently close (see equation ). Obliquity excitation (top panels) is accompanied by a decrease in mutual inclination (bottom panels). In some instances, the initial inclination is almost completely erased.