Yeah, that one.
Get Hoss's affinity pretty much as high as you can before he shows you the library and that will get it.
He's a book in braille but thanks.
its just easy thing like spending time with him, when he talks about working out say pilaties (or whatever its called) and the 2nd time tyson rushes out (after the convo about confessions) don't follow him stay and talk to hoss about family.