You must.

Or, if you don't, I want mine." "If you go alone, there are nine chances in ten that you will not get home in time for dinner, to say nothing of lunch." She looked at me oddly, I thought, and started to speak.

Whatever it was she was going to say she evidently thought better of it, for she remained silent.
Then I had a new idea.

Whether or not it was her look which inspired it I do not know.

I think it must have been; I never would have dared such a thing without inspiration.
"Miss Colton," I said, hesitatingly, "if you really are not--if you are sure your people will not worry about you--I--I should be glad to share my lunch with you.