Is it strange that my brother and I often share wine together?
Do you have a special relationship?
Not particularly, I just use him to hold my wine.
Even though you are mostly using him as a wine holder, it is good to share. That means that when you don't have some, he might share with you.
That seems selfish to me, I'd like to have all the wine to myself.
Yes, but when you share with others they grow to appreciate you. Sharing the wine with your brother requires only a small sacrifice, and gives you both time to bond.