Tom Riddle will NOT be Ignored
I don't have all that many Voldemort (I seperate Voldemort and Tom Riddle because my puny barely functioning Christian Coulson because apparently ever since I was a little girl I was like "that beautiful face, such a face card. Yes, he's evil but I refuse to accept beautiful man and gross snake man are the same character so I won't") and this particular headcanon is to explain how Diary!Tom seems to know so much about what has happened since he left his teen years.
The headcanon goes as follows; Lucius gave Ginny Voldy's diary, but its not for the reasons you'd think.
Since Tom is a somewhat caporal apparition of his teenage self he is somewhat confined to his diary and is all alone. That is very boring and he doesn't like to be all by his lonesome self and becomes quite a nuisance if he isn't properly socialized.
I am talking, he temporarily leaves the confines of his diary and harasses whoever he's in possession of.
Tommy here throws full on teenage, angsty tantrums if he's left alone for too long. If you ignore him he will make sure he is heard.
He cannot survive without people to listen to him talk and Voldy knows this about himself. But not self aware enough to warn Lucius. He probably thinks he's a fascinating companion to have.
Essentially Lucius was given a note to babysit Diary!Tom for the time being, which wasn't supposed to be long but we know was.
Voldemort: Oh and by the way, Lucius my slippery friend, along with feeding Nagini you are tasked with socializing with my teenage self in my dairy. He gets rather cranky when he doesn't have someone to talk to or manipulate so you must at least, and no less, than three times write in my diary and talk with him. It doesn't matter what you say, just have fun with it. Just don't forget where you put it, it's very important.
I think the real reason Lucius yeeted the diary into Ginny's cauldron is because neither he nor Narcissa could stand it any longer.
Cissa: Lucius, I cannot live like this anymore. Get rid of it!
I imagine that Lucius didn't right away jump to ditching it. He probably tried burning it first and then the next thing he saw was this, but imagine scorch marks:
Yeah, Tom was NOT happy about being thrown into a fire when he appeared.
I think he just appeared in Lucius and Cissa's bedroom as they were trying to sleep and had to list to Tom complain all night long.
