I've played a bunch of different versions of Walter [from "Fringe"]... I loved it when he was being random, which was probably the original version of him, more than anyone else. I loved doing Walter then, and all of the different mental states that we've played.

I suppose, when you start up in acting, you hope to be given challenges, and you always have dreams about the things you could do and couldn't do, but normally we get pigeon-holed a little bit, as we go on in our careers.

I'm truly grateful to the writers of Fringe for giving me that because, over the years, when I've spoken about the character with them, I've always felt that this would be the perfect way to end and complete his journey, and to complete the journey of this series, and they gave it to me.

I think main storylines are what always intrigued me, with those that were the relationships between the characters against whatever backdrop, whether it was in an ordinary universe or a universe in the future.

I love having played Walter because I suppose any actor brings a certain aspect of their own personality to their work, and I had a fairly broad canvas to paint on with the different versions.

Particularly in the final season [of Fringe], when we were shooting seven-day episodes with a reduced budget and big special effects, the team was so polished, by then, that we were able to do it and, I think, with incredible results.

We didn't know until really quite late in the piece how Joel [Wyman] would finish it off.