I have to admit that physically I based Ellis on a combination of an old college professor of mine and Lord Peter Wimsey -- not super-fit so much as underfed scholar. :D But this ties back into needing more description, something I have in my notes as "do this to the whole book" :D (Him not fitting with the pack was more an issue of tallness than of thickness.)

Jack isn't really the guest of honour, you're right, but Bell wants him to think he is, and he does have an important role to play. Ellis is the one with the big plans, but Jack is the proof in the pudding. And Bell wants to make sure Jack feels he's important.