"Thank you Severus, I really do appreciate your help with this." Receiving a message of gratitude was just as difficult for him as was passing it another, so he contuined working, not looking from the table of various potions each deadly in its own right. Usually the silence and lack of respect was something she understood and accepted, today though she was unwilling to walk from the room without at least being acknowledged. With extra loud steps of the foot she approaches his back, who refused to turn, mixing two of the ingredients together in a small vile.
"I am busy Miss Granger." Words dry just always.
"I said thank you, Severus."
"I heard you, don't you have to watch Weasley quidditch match?"
"It's customary to say you are welcome after being thanked, why don't you try it for once?" She watches his back and shoulders tense tightly, his grip on the small vile squeezes until she's sure the glass will shatter into the flesh of his hand.
"I don't need or require anyone especially a mud blood to tell me what to do and what to say. Best go before you are late." She gasps, eyes without warning stinging. It was just a word. A silly word, but still it hurt. Especially after he and her had come so far, enemies to mutual respect to a partnership in the labs.
"Fine, just fine. I don't see why even bother. You know, you claim that Harry and Ron are the most stubborn people to every walk in your presence. You however are the most in mine. I am sorry kindness is beneath you, I am sorry that everyday you have to wear a fucking mask of non emotions, but it won't kill you to let it slip once!" Again with extra loud steps she returns to the door and this time exits, closing with a slam.
"You are welcome, Hermione." He couldn't let that mask slip, not yet.