For a time loop suggestion and a link.
Link: Toms revival in GOF, (blood related) sets up the link. Played out When Tom strikes Harry in the forbidden forest with AK.
Loop would be between the night harry 'dies' and the night Tom was rebirthed. (Specifically Harry would return to the time during the graveyard)
Bonus points for some play on Harry's choice at 'kings cross' being the trigger sending him back.
Flowerpot link could easily be developed via Harry being at different places and times than originally after the night of the last task.
Example: Harry bumps in to fleur before departing from hogwarts. After talking a little fleur asks Harry to write/stay in touch; which he keenly takes up during his isolation in the summer following.