What does "One fancied things sometimes—fancied a fellow was looking at you queerly" mean from And Then There Were None?

Question

From And Then There Were None:

Well, he’d enjoy a chat about old times. He’d had a fancy lately that fellows were rather fighting shy of him. All owing to that damned rumour! By God, it was pretty hard—nearly thirty years ago now! Armitage had talked, he supposed. Damned young pup! What did he know about it? Oh, well, no good brooding about these things! One fancied things sometimes—fancied a fellow was looking at you queerly.

I am not able to figure out what the line "One fancied things sometimes—fancied a fellow was looking at you queerly." is trying to say. And why is there a dash in midst of the sentence, also what do these dashes usually mean?

Answer 1

• ‘Fancied’ here has the meaning ‘was inclined to believe’ or ‘thought it a possibility’.
• ‘One’ is effectively being used as a pronoun, meaning ‘I’. General MacArthur is talking to, and about, himself in a superficially formal and depersonalising way.
• ‘Queerly’ just means ‘oddly’.
• The dash indicates a brief hiatus in the speech or thought.

So the whole ‘ One fancied things sometimes—fancied a fellow was looking at you queerly’ can be read as

I was inclined to believe things sometimes… thought it a possibility that another man was looking at me oddly.

What he is talking about is that he can never quite know whether his associates in the army know of the role he played in the death of his wife’s lover. He interprets their odd looks as potentially conveying knowledge of his actions.