This started as a small response about the ending then turned into kind of a mini-break down Bruce's relationships with the people close to him and a mini-character analysis of Selina... WHOOPS, I don't know.
Seriously read at your own risk, it completely ruins the ending, but I really want to discuss it so...
CLICK THE READ MORE TO READ...MORE. :)
I have thought about this so much since I saw the movie and I have so many different ideas about how they ended up back together.
Basically, what I believe happened is Batman ejected, found a way back to land, sneaked back into Gotham, and tracked Selina down quietly. (How he did the first 2 I will never be able to figure out.)
I don't think that he left Gotham immediately. I think he stuck around a bit to see how things settled down, to see how the city recovered, to see that everything in his will had been carried through, and to make sure Gordon, Blake, and Fox got the messages he had left them (mostly, the message that Bruce was still alive).
As for Alfred, I like to believe that Bruce kept continual tabs on him even after he left Gotham (somehow... with some of his Bat gadgets or SOMETHING) and specifically waited for him to go on vacation so he could reveal himself to Alfred in the way that Alfred had always hoped to see Bruce. In fact, I like to think that Bruce so badly wanted to show Alfred that he finally was doing what Alfred had always wanted him to do -and that he was happy (knowing that would reassure Alfred that he had, in fact, NOT failed the Wayne family)- that he and Selina may have actually settled down in Florence for a few years after leaving Gotham. I like to believe that their meeting was absolutely not by chance and was meticulously and methodically planned out by Bruce.
But that's just me...
As for what happened between Bruce and Selina... I really love that Nolan made it to where people could come up with their own Bat and Cat reunion for themselves.
For me, I imagine that Selina didn't have any idea that Bruce had survived or had planned to try to survive. I think the part of Batman that was self-sacrificing was something she really didn't understand because it was something she had only recently discovered in herself. Before she gave up her escape to come back and save Batman from Bane, her life experiences had taught her the only way to get by in Gotham was to look out for herself first.
The way Batman was prepared to die for the city was something so new and foreign to Selina, I don't think it would have occurred to her to question it. Of course Bruce had died, because it was the the very same ending she had risked for herself to come back to save him. Therefore, after the bomb goes off and the city is saved, I imagine she is pretty devastated. Might she have hope that he's alive? Probably, but I don't think that she would have allowed herself (once again, with what her experiences have taught her) to ever believe in that hope.
So I like to think that Bruce went straight to Selina as quickly as possible after he escaped the bomb. Since she wanted to leave town before the battle, now that Bruce is seemingly dead, she'd probably head out of town even faster so he'd need to get to her ASAP so he wouldn't miss her.
I keep picturing the reunion in her apartment in Old Town, but she probably wasn't there since everyone was kind of just living where ever during Bane's occupation... so I don't know... But I imagine the reunion is really sweet. I'm sure there will be COUNTLESS versions written into fan fiction but ...
Basically I think, had Nolan decided to film this, it would have shown Selina visibly upset alone in her apartment -because everyone else is out celebrating that they didn't get blown up- (possibly crying, or at least has obviously been crying) getting ready to get out of town, maybe with the coverage of what happened earlier that day on the news on in the background. I also keep imagining that Bruce reveals himself to Selina with some sort of well-timed response to whatever is said on the TV, but that kind of seems inappropriate. I actually think in this situation Bruce would just want to let her know that he isn't dead so badly that cutsie introductions like he's used before have no place here.
I think she'd be so overcome and relieved about Bruce being alive that she wouldn't think to hide her feelings, there would be some hella embracing and kissing, and it would be GLORIOUS.
Then, they both would probably head to Wayne Manor, grab a few things they need (including his mother's pearls), then find a way to go into hiding nearby so Bruce do all the things I outlined at the beginning of this HORRIBLY long post.