I knew from the time we got Indy that when he was reliable around the house that we would get him a companion.
After we lost our first Boxer, Rocky, my greatest regret was that he lived most of his life as an "only dog". He loved people and other animals, and interacted with both very well.
When we got him, we had an old female Afghan hound. As a puppy, he tormented the old gal by feigning attacks, trying to get her to play. She would play some, but also wanted her peace and quiet.
Once he learned his place, they got along famously until she passed away when he was just over a year old.
When we got Indy, I vowed not to make that mistake with him. So, when he was about fifteen months old, his half sister, half cousin Ava joined our family.
Tom