how the heck you get sal's rote? I've been skipping classes to see him but is always the same interaction when he smiles at you..
I think you need to get into one of the classes he's in first! You can also open the game guide, but i'll write it here for you.
Don't forget to have 8 STR points!
Take Arithmancy, Astrology, History of Magic, Study of Malediction as your classes! During Arithmancy/History of Magic class, click on him. Even though you can't find him, make sure that some students are talking about the 'Nightshade Dragon'! Then you wait until almost the end of the day and I think MC will go down to investigate about the so called 'Nightshade Dragon' and run into Sal. (Don't pick just keep resting, that's an auto-fail). The choices I picked were, "Yes, I'm a student" and "Well he seems to know what he's doing." Then I think, during lunch, approach him! I chose "Well, you found me." during that convo! After that, I went to either the fields, or the garden or the forest and then chose the option to wander around. Then you'll find him again! Also be aware you need 8 STR so you can pick the choice to say 'Confirm'! Then during History of Magic (Or something else?), you click on him again and pick the choice to save him a seat. I forgot what happens next but then you go to the library (during.. 6 PM?) and work on his project! At the end, you pick "We are friends." and then you have it! Sorry for the long paragraph brhj