Bane is basically a setup of a character that gets lost in his own loop  hole.  He really had no plan, other than do whatever Talia wanted; and  that called for escaping from the Pit with Talia and being trained to  become a member of the LOS.  Later on, when Ra's gets an idea that he's a  bit of a rage monster with zero control and banishes him from the  League.  
Meanwhile, I 
guess Bane does practically nothing  between his banishment and the events following after Batman Begins  until Talia finds out her father dies and calls upon Bane to be a  mysterious plot device for her plan.  The movie implies that Bane's only  real motivation is doing whatever Talia wants, but I like to think he  was doing as he pleased too.  It's safe to guess from being in the Pit  for so long for reasons that could be similar to Vengeance of Bane, his  view is of a prison world.  And with that, he sees Gotham as an even  greater prison and Batman the warden: logically, his mindset tells him  to break the Batman, and from that he becomes the top dog. 
But  at the same time, it doesn't make much sense, does it?  Why would he  want to rule Gotham only to be working under Talia for her love?  Not to  mention if Gotham were to become his and become another Pit of Despair,  if you will, why create a temporary prison to blow up?  There's no real  follow up, and you would figure he would be aiming for a greater evil  that would be a bit more permanent. LOL  
And how it sounds on  Talia's end, she sounds like yet another stupid woman we know of that  has daddy problems.  I can't blame her though!  All of her life she grew  up in a prison with her mom only to see her be killed.  Dad's not  around because the War Lord found Ra's marrying her daughter behind his  back.  For that, he sends his own pregnant daughter into a raging hell  and makes Ra's an outcast.  
That part makes perfect sense.  
Later  on in the Pit, she befriends Bane; she's found a big best friend that  protects her and he has his own little Osito.  Basically it's a romance  between Chewie and a female Han Solo, minus how pedophile-ish it may  seem.  But then again, I can guess at this point when Talia escapes,  she's between 8-10 years old, and Bane is probably 16 at the time.  
On that side of the world, that makes sense. 
When  she escapes and Bane helps her in the process, being brutally beaten in  the process, it's probably shortly after Talia finds her father (who's  already begun creating the LOS) and they go into the Pit to save Bane.   I'm surprised it took Ra's that long to go out save his own daughter,  but at the time he probably didn't know he knocked up his wife before  sending her to her death.  I won't be picky and question that to no  end.  ANY WAY.  He finds out he has a daughter.  To make up for all the  years that he never had with Talia, being the irresponsible father he  was, goes over and saves her boyfriend from the pit.  Ra's probably  thinks "hey, he seems like a nice guy: takes care of Talia when his wife  killed, gets beat to hell so she can escape.  What the hell!"  Ra's,  Talia, and the League finally go barging into the Pit to extract  vengeance on everyone there and save Bane.  What could go wrong with  this fantasy of a morbid fairy tale ending? 
With some  consideration Ra's takes in Talia and Bane, trains them to be members  from the LOS.  You never see Talia use this hand to hand combat and  skilled ninjitsu, but other than that... once again, it's a rational  train of thought. 
After awhile, Ra's sees that Bane has anger  management issues and has probably gone through 40 different members of  the League like toilet paper, and decides enough is enough!  Pulls his  thoughts together, gives Bane a slap on the wrist and excommunicates him  from the League because he's a reminder of his wife and the hell he  stuck her in... and that he probably hulked out too much when he  shouldn't have and killed about 42% of the group he invested years in  making.  He DID take the time to get his newly formed order to save his  @$$ from the Pit.  And in return, kills almost half of them, or safe to  assume that he does.  What other kind of reckless behavior would you  expect from a group of deadly assassins that would make Ra's a little  ticked off?  In the eyes of Ra's, Bane is a reckless hummer driving  douce bag monster and doesn't deem him fit for his daughter. 
If I was a father and just found this out about a daughter I never knew that I had, I would kind of feel the same way. 
With  Bane gone, I guess Talia has a b*tch fit and never speaks to her father  again.  So for years on out, she then ONLY decides to forgive her  father after he's dead.  Talia's pissed because she's under the  impression that Ra's only excommunicated Bane because he loved her.  It  could VERY WELL be the case, but again... I won't question it. 

   So Talia leaves because she's pissed with daddy for taking Bane away.   She never speaks to him or comes around to forgiving him until she finds  out Batman murders him... which, let's be honest, DID. LOL
And  because Ra's failed to cleanse the world with an Ozymandias like motive  (that has its benefits in an overly extreme way), Batman within 8 years  is able to purify Gotham for the most part with the help of Dent and  Gordon... without killing anyone.  Minus Ra's, who he left on a train  with no rail and a device that could explode at any time.  And Harvey  Dent... because he got butter fingers and dropped him accidentally after  shoving him off of 6-10 story roof only moments earlier.  It was a lie,  sure, but most great things come from secret lies.  
So in a nutshell:
-Talia  in a angry PMS fury, devises a plan to destroy a Gotham that's already  been, for the most part, saved, with the help of Bane whom considers  only a friend at this point after fooling around with Bruce.  
-Bane  is friend zoned and does everything in the name of Talia's love while  attempting to have his own fun along the way.  Which includes breaking  Batman, putting him in the Pit that he endured for years for reasons we  can assume that was created by Chuck Dixon. 
-The Emperor  Palpatine of the story, Talia, makes a half-@$$ed plan as an apology to  her father who shouldn't have been fooling around with his bosses'  daughter in the first place, and in the process marrying her as an  apology for not wearing or breaking his condom.  
-And from  there, Talia takes advantage of Bane's love and makes him do all the  hard work as a grand master dictator... While she dolls up for a board  member job in Wayne Enterprises, only to throw parties and screw Bruce  Wayne on the side because she's a typical artificial b*tch.
THAT'S where the tires fall off for me. 
