The reality is that we love TV, no matter which realm it takes place in, so if a show can successfully pull off an alternate universe episode (or episodes, or full seasons for that matter), we're on board to travel wherever they want to take us.
"Grey's Anatomy" is the latest show to explore how things might've been. Its latest episode, "If/Then," (airs Thurs., Feb. 2, 9 p.m. EST on ABC) gives viewers a glimpse at an alternate version of Seattle Grace and the drastically different lives of the doctors we know so well. Of course, things will snap back to normal next week, but it's fun to explore how things would turn out if a few variables changed.
Some shows take it a step further -- "Fringe" has been flip-flopping between two universes for seasons now -- but there's always a constant: If you care about the characters on a show, you'll watch them no matter how crazy things get around them.
Check out a few of our all-time favorite alt-time episodes.