] I feel sorry for all the Tilney children. I think they all suffer under their father's roof. Even the eldest found a profession to get away from it. I see no evidence that the three siblings do not get along. Quite the opposite. From Chapter 7, we hear from Eleanor that "both my brothers are very affectionate"

What are the Tilneys' ages? Henry is 24, so Frederick about 26 and Eleanor 20 (is that right? or am I confusing her age with IT's?) Didn't their mother die when Eleanor was about 12? If so, then Frederick would have been 18 - and fully able to leave home & join the Army, perhaps out of an adventurous streak, a desire to get away from the pain of his mother's death, a desire to get away from a home now completely dominated by his father (without his mother's softening influence), or a combination of all those. Although Henry was a tad young, he might have been able to leave - but he chose to stay out of concern and loyalty for Eleanor. Actually, she was alone with her father much of the time, wasn't she? She mentioned her lack of companions - maybe that was after Henry started attending to his parish down the road.

I'm starting to think the "missing mother" is a key figure in this story. Next time through, maybe that will be the thread I follow.

I agree with Cheryl (just below) that Eleanor included "both her brothers" as an afterthought, but my interpretation is closer to yours, Siobhan. Of course Henry comes immediately to her mind, he is her frequent companion. She rarely sees Frederick, and it's been that way for many years. (He's a captain already, he's been in service for some time.) That doesn't mean she doesn't sincerely like him or that their relationship is not affectionate. I think she does like him.