Two twins A and (evil) B. Twin A remains "stationary" while evil B goes at near light speed to-and-fro. Ignoring General Relativity (acceleration/deceleration) evil B experiences time dilation and as result, when they meet up again, B's clock is behind A's clock. Look at it from B's point of view, B is stationary and A goes to-and-fro. Why won't A's clock be behind B? Why doesn't A experience time dilation?