I think the main reason Walt is so loyal to Jessie is the guilt he feels at letting Jane die. When he did it he thought he was just finding a way out of a problem only to realize later how wrecked Jessie was over it.
I also think that Walt realized Jessie's point about using the kids and the unseemly side of the trade. The contrast between the sterile lab and the gritty street is remarkable. He's starting to come out of the lab. The funny thing is, as much as he has distaste for that side of the business, it looks like he has to go there if he wants to reform it. However, once he goes there I don't think you can come back.







