Dying Mob Soul Ghast Absorption

With the new beauties (happy ghast) being added, please make it that when a mob near a baby ghast dies, it would size up by "absorbing their soul." The friendlier the mob is (like fed tamed wolves), the friendlier the ghast will be. If bad (not undead) mobs die (like vexes), the ghast will become more evil. If you kill the mob, the absorbed soul would kill you.