it all started for me when I was 5 years old...
My parents made the mistake of letting me watch Aliens at that age... it gave me reoccurring nightmares!
My parents took me to a child psychiatrist, who did nothing but tell them they were bad parents for letting me watch that movie at such a young age.
By older brother, told me they were chocolate monsters, and then I "stopped having nightmares." but I have been obsessed ever since.
Predator followed shortly after... I was a fan of both franchise independently before the AVP series started up (I hated the AVP movies, but love the comics/books/games).