Hello.
I have a book about Hell - it has an Imprimatur, I think … it is orthodox - anyway, the word Hell is in big letters on the front book cover. It’s actually very comforting to read because it has a section on how to avoid Hell.
Good to leave sitting on a table somewhere. Also orthodox books on exorcism might help. Not wanting to go to Hell is not the best reason to turn to God, but it is a start, and bringing up the consequences of turning from God, in a clear way, can be helpful.
Oh, when I was younger and in a really bad state I wouldn’t go near anything by Thomas A Kempis.
It might help to get some holy water, maybe a little font at the exit doorways and have holy cards around. Sprinkle your friend with some, with their permission.
Also, I have this book called “The Bad Catholic’s Guide to Good Living.” Something easy & fun to read might be a good choice.
But, there’s nothing like continuing to love your friend, pray for them and give them your own good example. God gives us all free will and we must respect other’s choices. Doesn’t mean accept the choices, but respect them.
My two cents.