Hey Stephen, if you're interested in becoming a character animator, then the best thing to put into your demo reel would be performance shots and maybe some physical shots to demonstrate your understanding of physics and movement. Performance shots can be any kind of pantomime shot or dialog test which shows the character acting. The key is to come up with interesting and entertaining ideas in these shots. Something that has a setup and payoff...like a gag of some sort. Try to come up with sincere acting that shows the character thinking. Choose acting choices that are unique to your character and show clear ideas which support what he's thinking. You don't need to show a ton of shots. I wouldn't even go over one minute in this demo reel. One minute of animation which demonstrate the things listed above will be enough for an animation supervisor to determine whether you can be the right fit for their studio. Good luck!