The Blue has a will on its own and wants to create a Blue-based superintelligence
The Blue of an Agent may as well be considered sentient if "Alex" is any indication and he is certainly eager to encourage Vera to activate Huldra in a way she could be receptive to (bringing back the true Alex to life) and is notacibly less human when really excited by the project.- The way Stina talks about her own experience with the Blue and its adaptability may imply that she is experiencing something similar (probably exploiting her desire for power in this case) and if Vera had to accept the death of Alex to get rid of "Alex" then Stina is certainly unstable enough to be vulnerable to her Blue.
