Chemistry. The most elusive concept to grasp, the most impossible element to fake, and the most important factor in how audiences perceive relationships. Chemistry has been stumping show runners and casting directors for years because you can't write it in, you can't force it, and you really can't sell anything without it. That is why chemistry tests are such a vital step in casting love interests on TV shows and movies. But the power of chemistry is not just limited to love interests, it applies whenever you put two actors on screen and expect them to interact, and Arrow hit the nail on the head when they put Stephen Amell, Emily Bett Rickards and David Ramsey in the same scene.
Source: giphy.com