Chris TIlly has reported a few additional details about John Wick: Chapter 2 in an article for IGN. Keanu has said the following:
Kind of evolving the action – if the first one was a black belt, then this one is third degree black belt. It’s such a fun project and a great character.
“Laurence has this fantastic role as a character in the Underworld called The Bowery King. He plays such a great character in the piece and he brings of course humour, intelligence, charisma and fascination – he’s such an incredible actor and it was a pleasure to work with him again.
“And Peter Stormare – Stormare has more of a cameo in it but again he brings such fun and mystery and this mixture of groundedness and the surreal.”
Note: I ‘m assuming Keanu revealed these details during his interview with Tilly (covered here) for the Exposed release in the UK.