A new featurette has John Bell introducing Dui (pronounced Dewey) who plays Rollo in Outlander season four. John speaks about his training and working with him on set, as well as some peeks at new scenes featuring Rollo. John Bell also shared some photos of Dui and his brother bonding with him outside of filming. Screencaps of the new footage are below the video.
https://twitter.com/JohnBell/status/1050513882459062272