In fact, to show just how self-centered she still is and how them saving her means nothing (since she's dying soon anyway), effectively deterring her own insecurities about relying on others, Bela sells the Winchesters' location out to Gordon for a priceless mojo bag when he holds her at gunpoint. She calls Dean and tricks him by pretending she's thanking him for saving her, and out of guilt -- her first actual character development -- she locates Gordon and calls back to warn them. Unfortunately, her good intentions don't last long, because she comes back and pretends to assist them with a dreamwalker claiming that Bobby helped her in Flagstaff just so that she can get close enough to steal the Colt. In this case, it's not even about proving that she still has it in her to be self-centered. It's genuine self interest and disregard for Sam and Dean's lives that motivates her to steal the Colt.

After setting Dean and Sam up to get captured by Henriksen, Bela sells the Colt to the demon Crowley in an attempt to buy back her contract. He changes the terms of the deal and tells her she needs to kill Sam. After getting accosted by an angry and desperate Dean who's looking for the Colt, she tries to hunt them down and shoot them in their beds, but winds up shooting sex dolls instead because the boys are two steps ahead. Rather than show any bitterness about their outwitting her, she rewards them by using her dying moments to provide them with information: Lilith, the demon who holds her contract, also holds Dean's and it's her that they'll have to kill to get him out of it. By this point, she's learned that maybe, just maybe, it's fair to trust these boys to be able to assist her in doing things, as difficult as it is for her to admit it. It took until her final moments for Bela to finally manage to put trust in someone other than herself, and she never got to live to find out if it was rewarded or not.