Captain America - Civil War: 10 Characters Martin Freeman Could Be Playing

In the comics, Civil War is kicked off when an irresponsible group of superheroes allow a super-villain they're pursuing to blow up a neighbourhood, complete with a school. As a result, the general populace recoils in horror and demands accountability from all heroes. A similar setup is likely to occur with Crossbones as said supervillain, and coupled with an already existing accumulation of bad will as a result of Hulk’s African rampage and the creation of Ultron.

It’s almost a given that there will be one focalized character to represent the entire populace’s hatred of the Avengers, as it's an effective way to humanize their pain and anger. It’s a very essential role, as we need to be able to see the Avengers from another POV, one that allows us to understand the need for some sort of registration or government oversight program.

This role was portrayed in the comics via a mother whose child died in the blast. She initially blamed Tony Stark for inspiring the ill-prepared heroes, but came over to his side when he became a public advocate of the Registration Act. It's very conceivable that Freeman could fill that exact same role.