Hawkeye

As revealed in Avengers: Age of Ultron, Hawkeye has quite a few reasons to be against the Registration Act. In his way, to everybody's surprise (well, not exactly everybody's), he is revealed to be a family man, already married and with children. So we can see that he is actually a very discreet individual, to say the least, who cares a lot about keeping his private life private.

The Registration Act would force him to renounce his privacy, so it would be understandable for him to side with Captain America during the events of Civil War.

As seen, Jeremy Renner is pretty explicit as to which side his character would choose.

Of course, it can be added that this may change, since his family can be used as a leverage, to convince him to actually join Iron Man. We doubt that this will happen, but still"¦

On the next page, Black Widow