My first "official" rescues were Peeka and Boo, sister and brother. They were like one cat, inseparable. Peeka went to the Bridge at age 14 w/acute renal failure and Boo (now 18) was so protective and comforting to her that it made me cry. I said to him once "Go comfort your sister; she needs some cuddling" and he immediately went to her, laid down next to her, put his arm around her and from that point didn't leave her side. When I took her in to make her trip to the Bridge, Boo was simply lost and he looked for her for days and would sit in the middle of the room and just stare. If I was still actively involved in rescue/adoption, I'd take in siblings in a heartbeat. You give and receive twice as much happiness that way.