Mike and Bonnie were simply bad written IMO.
Mike was known to be a team player, a handy friendly guy who always wanted to help. I even appreciated the attention he had for Arvo, it showed how kind and good person he was behind the brute and strong man, but if he feels sorry for the defenseless teenager that we just met being bullied, why would he screw AJ or Clem, even younger and more fragile human beings, taking all their supplies? Simply makes no sense.
Bonnie was kind and protective, kind of a mother figure to Clem, giving her a coat as a gift which she is always full of herself of, even if Clem doesn´t like it. She also was the only kind guard to Clem among the bossy guards at Carver´s camp, and was willing to help Clem´s group by any means she could, driven by good morals and to get forgiveness for capturing their group. At the campfire, she was concerned about Clem hearing about sexual themes, like a mother figure would. Then she can flip out and blame the kid for Luke´s death, while i though that only S2E4´s broken Kenny would be capable of doing that. I would never guess she would be broken to that point, only Kenny would. Lots of time she was holding AJ too and concerned about his food. After everything she just tries to leave AJ and Clem without supplies? Why she didn´t at least told and Clem about her plan? That´s totally out of character for me.
They should have some consideration for Jane too, considering they were glad she was back to the group, even though both weren´t so close to her, but why they were fond of Arvo, who they just met, over Clem, AJ or Jane is unexplainable.
TL DR These 2 were as unconsistent as Rebecca and Carlos from S1E1 to S1E2