Brother-to-sister 'Tanya' is neutral (equal-to-equal), so it can be used with anger/love and this is ok. Emotions are expressed by voice tone in this case.
Anger can be different. He also can use formal 'Tatyana' to express cold anger: "We are gonna to have serious conversation, Tatyana!"
But also he can use mentioned above 'tan'ka'/'taniukha' - extra-diminutives - to imply that he wants to talk from position of older / more significant person: "You are such a pathetic fool, Tan'ka!"