** SPOILERS **
Jesse = Shane. The character arc is there: enigmatic sidekick; both are under the thumb of manipulative women (they also bear a resemblance) in the early seasons of both shows; drug addicts; Vic comes to the rescue of Shane (against the Armenians), Walt comes to the rescue of Jesse. These secondary characters become the main characters’ primary foes. Breaking Bad obviously ends it on a far more positive note.
The family dynamics of the main characters are quite similar. Both have emotionally/physically challenged children. These are either used as a tool to keep these characters oblivious or to gain sympathy from the audience. Both wives start and end in similar situations.
The germs of these ideas are contained in The Shield:
• Colored drugs
• Walking naked through convenient store
• ‘'Money train’' is one of the bigger action sequences in The Shield. It is the term for an Armenian money laundering operation. In Breaking Bad, they quite literally fleece a train in one of the larger choreographed action sequences.
• The way the money is stashed and moved.
• The idea of going off the grid. Pretty much all the main characters in both shows entertain the idea. We see the process play out.
These are things I picked up without even trying. There are many parallels in their rhythms.