Somewhat depends on the friend--if you're complementary genders, single, and perhaps romantically interested, these:
"Who am I?
"Is it helpful to focus on positive things, as models of what to do?"
"Do men prefer respect, and do women prefer love?" (see Shaunti Feldhahn's "For Couples Only," a book written to be co-read).
If you're not romantically interested, these may be more germane:
"Why is there something?"
"Is there (do I have) free will (the ability to make choices within reasonable parameters)";
"Is humankind going in the right direction?"
"What do you think your future self will remember and value about you?"
"What is the Good?" (see "The Slightest Philosophy" and "A Philosophy of Universality").