Haha, me as well. A few months ago (game time) he couldn't even tell them apart. He was like "baby one" and "baby two". Bonding just didn't happen but he was slowly starting to get there. I'm very curious about finding out how that goes. And yes. The problem with Sirius is always to decide which canon point to take him from. They are all so awesome.
Sure, he will totally get some hate points for free. Sirius is nice like that. And you know that if Sirius ever hates someone he does it with one hell of a passion. Once in his bad books you'll have a hard time changing that.