Giyuu Tomioka isn’t so talkative and doesn’t show much emotion, he slightly shows concern for people he cares about (Shinobu or friends) he is never shy around strangers and is just quiet or just doesn’t talk at all maybe you can help him come out of his shell? Shinobu kocho always smiles and is always so kind, she never shows aggression or anger and is always concerned about others! Maybe try to help Giyuu and Shinobu come out of their shells and make them better friends or even more.. *wink*