These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: From Fake Dreams
Base Breaker: There are a lot of people that dislike Sirius, and a lot of people that will defend him.
Nightmare Fuel: Medea turned her Master into a living wand... which involves putting her in a test-tube, unable to scream or move.
OT3: Rin seems to be aiming for this with herself, Sakura, and Shirou.
Though Word of God states it will become a harem, eventually.
What else could you expect? This is Nasu-verse, after all. And Shirou is protagonist. With BAR.