Idea for a new spell/curse

I have spent many days pondering over my target and how to attack a second time. I have targets hair, and my own blood is in endless supply. I have pondered if i could somehow keep what i cast bound to my target indefinately using my own blood, but am aware that there is a risk i may target myself unintentionally. I have also contemplated getting one of the targets dolls and having it possessed demonicly before retrieval. I have also contemplated getting invisible ink to etch a curse onto my targets belongings before they are retrieved. But in all of this I must also ensurey children are not affected nor targeted. I do a lot of improv magic, and often spend great deals of time going over loop holes and sealing them, defenses and getting around them, and most importantly, making sure it can not be undone and reversed.

My target is an Italian Roman Catholic, although i have never seen my target actually use any prayers. The most i have seen is smudging. Easy enough. However my target is known to go to others for help and that os a wild variable difficult to account for.