Blair and Berlin are similar in some aspects. Both were manipulated into wanting enemies of the Cabal (Red and Liz) dead due to the loss of family members (Blair's mother and Berlin's daughter) that were actually due to the Cabal.
Nasim Bakhash and Milton Bobbit operated in the same way. They worked as contract killers until they saved enough money to fulfill their personal contracts. In both cases Reddington was interested in their client list.
Anslo Garrick and Luther Braxton operated very similarly. They were highly miltary like mercenaries that were both able to break into high security buildings. Besides the fact that both were given two episodes.
Sir Crispin Crandall and the Longevity Initiative were very similar. They were both looking for imortality. They saw the brain as the path to imortality. They were both inspired by sea animals.