That's a great sibling relationship.
My brother and I share an apartment half the time when he's not traveling. When I lost my pup, he opted to stay back more so I wouldnt hole myself in the apartment 24/7. But that meant dropping out of projects and I felt really bad when I realized this.
Even now, I hate admitting it to him, but he knows me better than myself at times. Like at family gatherings when we all share food and drinks, he'll swap out my straw for me with the clean one after everyone has had their share. He'll take the middle seat because of my random motion sickness when he's much taller and gets squished.
He still takes on certain responsibilities because he knows how I am.