In my case, my MC IS the straight man, so I'm not sure how to give him anything funny to say or do.
Get ahold of the original British version of
The Lord of the Rings. Aragorn has a sense of humor in it.
This was removed for the reprinted American version (long story short: Under the copyright laws of the time, since there hadn't been an American edition of
The Lord of the Rings when it first came out, LOTR was in the public domain in the USA. Ace published it, as public domain, with no royalties going to J.R.R. Tolkien. In order to get it back under copyright, a new edition had to be created, and it had to be substantially revised. (You were wondering about the author's statement on the back cover of the Ballantine edition, "Those who approve of courtesy to living authors will purchase this edition and no other"? That's what that was all about.)
What was substantially revised was revising Aragorn's sense of humor right out. Made him more kingly, I suppose.
Example: Aragorn has just looked into the Palantir. Gimli asks, "Did you say aught, to him?"
In the revised edition, Aragorn replies, "Nay, Gimli...."
In the first edition: "What did you fear I should say? That I have a rascal of a rebel dwarf whom I should gladly exchange for a serviceable orc? Nay, Gimli...."