As with speech therapy, people who buy books, take the older kid to classes and so forth have mixed feelings about whether those things helped: some say they do, some say they don't, some say they're not sure. The followup stories are well within the normal bounds of sibling interaction. One thing I did notice from reading and talking to people: tandem nursers swear that made a big, positive difference in establishing good feelings between siblings right from the beginning (cosleepers/bedsharers report similar, but usually a later effect). It doesn't _stop_ negative interactions, but goes a long ways to providing balancing and/or compensating positives.
In the recovery room, T. watched A. closely, but with a lot of suspicion (a little shy of what R. and I call the "hairy eyeball"). Later in the day, we got them both on me at once (tricky, what with the IV -- which T. wanted to remove -- the catheter -- which he kept bumping -- the incision, ditto, and the sore uterus). T. watched A. in action there with something resembling equanimity. By the next day, he was patting his sister after he was done with his tap, saying, "Baby". And smiling.
He's been very cooperative since returning home, careful to avoid hurting me and when reminded, careful to avoid crawling on A. This evening, he reached over (while NOT nursing) and played with her ear briefly (she gave him the hairy eyeball, but otherwise continued nursing). He and R. play with each other's ears when watching TV in the evening, and T. will play with my ears occasionally, and the various women who have taken care of him over the last few months. I don't recall if he's played with grandma's ears or not, but he's pretty conservative. This is a strong indication that A. is in his inner circle, and regarded with some affection.
I'm still waiting for the biting, pinching and other get-a-reaction maneuvers so characteristic of toddler siblings. But I'm a lot less worried about having to manage the kind of longstanding hatred and resentment I was on the receiving end of from my older sister C.