I second this because my brother was just like that.
The only FE he ever played was the Awakening Demo from way back, he liked it but never played the full game because I recall he was into Dues Ex human revolution at the time.
He didn’t touch Fates because he didn’t appreciate the multiple routes “again with this Pokemon bullshit??” was his direct quote.
He finally tried out a FE game and it was Three Houses, I was surprised he liked it way more than I expected and it was fascinating to see a view point of a completely newcomer.
if you’re curious: he picked Blue Lion and he ABSOLUTELY HATED Edelgard’s guts. He refused to play Black Eagle afterwards both here and Three Hopes