This question contains spoilers…
(view spoiler)[Last Olymp:Foreshadowing or overthinking? "…today the House of Hades will be called the saviors of Olympus."(317) Book title origin? "I caught her hand as the pavement fell, crumbling into dust. For a second I thought she was going to pull us both over.”(321)Teaser for their fall in MoA? “Hera whirled away in a huff, but I figured our lives would be safe, at least for a little while.” (343)Hera’s big role in HoO? (hide spoiler)]
Did I plan those? No. But you would make an excellent English teacher, finding foreshadowing!