talking to Mia is a little bit confusing - the topic 'poison fruit' is available before the event even happened.
easiest fix is probably replacing mia.rpy::125.
instead of
"Topic 01 | Poison fruit.":
something like
"Topic 01 | Poison fruit." if nscene07.watched:
works nicely - the variable is set to true at the end of the food poisioning scene chain.
keep up your great working, I am very curious to see the story develop