Our youngest niece despised her baby brother (“baby bwudder”) for a couple years; they got along okay when he got old enough to be interesting. Then their parents got divorced, and until she left for college this year, she was her brother’s defender and supporter and protector and confidante.
Congratulations! Also: sympathies for what you’ll go through in their teenage years. A couple friends used that time to experiment with new hair color, since they needed something to cover the grey hairs that appeared on a daily basis.