Why was Harley Quinn still "behaving" by the end of the film?

Question

The basic premise of the Suicide Squad movie (and most other incarnations) is that Amanda Waller keeps the villains under control by implanting a bomb-like device in their necks. They obey her orders in large part because she can just kill them at any time.

By the end of the movie, it would seem that Harley Quinn should no longer care about this, because

Joker manages to disable her device, and they never implant a new one.

But she continues to act as if she's scared of what Waller might do to her. Did they ever explain why?

Answer 1

Are you sure she knows it's disabled?

As far as I saw, after Joker disabled her implant, the text he sent was just "it's time, come now" or something like that - she came because she trusted him, not because he sent details of what he did to make her safe. And I don't know how much of the details of that might have come up in conversation before they were separated again.

She might not have known that the device was disabled, as opposed to temporarily suppressed. She might not have known, if the device was actually disabled, if Waller etc had succeeded in turning it back on at any point afterwards (at least, not have known until it was too late). So she acted as if it were a threat again, because she didn't have a reason to know that it wasn't.

Also, I recall the team reacting because they're afraid of the bombs, more so earlier in the film - a couple instances of "if he dies, we die" to get them moving, and such. By the time the device is disabled, she has a connection to Deadshot and Diablo, and so comes back and stays to watch their backs and because if Joker was gone, she would have nowhere else to go - and she goes to the final fight because she is persuaded, not afraid. That would cover most of her actions after the implant was disabled, until the very end and going back into custody. That is trickier to explain if she did know the device was disabled, but might be explained by the threat to her new friends (who she does seem to care about by now), the bribe of the espresso machine Waller gave her, and possibility she wasn't sure if the device was or could be reactivated at some point.

Answer 2

The answer is that Harley is a romantic and will do things because they have Romantic implications. She's often shown in the comics doing things specifically to promote love between people. In this case it was Flag and June Moon.

Beyond that, she thinks of the whole thing as fun and a wild trip. That is part of the reason for the scenes that show her origin stories. "Are you willing to live for me?" This means, are you willing to live and be damned the consequences. In the case of the bomb in her neck, she doesn't want to die, but she's not going to be forced to do anything she doesn't want to do because of it so it really doesn't hold any power over her to begin with.

This has always been a mistake that the writers have made with the Suicide Squad, not because Harley wouldn't do it. She's been shown to be a force for good in many places, including being an avatar of a New God against the Darkseid. The reason it borders on bad writing is that Waller would likely never make this mistake, but then again, it is shown that Waller is arrogant and often makes dumb mistakes.

Another aspect is that Harley, probably, likes Lawton, Croc, and Diablo. They are also "bad guys" but the heart of all those characters are neutral or good. Lawton is a hitman, he's not a killer. Diablo is a crook, but he never set out to kill unnecessarily. Croc a good guy with a genetic mutation that makes people fear him and is slowly destroying his brain. And Harley herself only does all the crazy crime stuff because she's in love with Joker and is trying to impress him, make him love her, etc. She's not just crazy like many want to portray her. The fact that she is this way and can read the others (probably has read their psyche profiles), is another motivating factor as to why she returned to them and went along with them.

Answer 3

In the absence of her puddin', Harley seems to view herself as being part of the team, at least according to the film's official novelisation

“Hey, Craziness!” the deep voice called to her. She turned, catching the baseball cap Boomer tossed to her. She laughed as she dropped it on her head and thumbed it to a sexy tilt.
Like it or not, she was one of the guys.

In the absence of any genuine authority figures telling her what to do (and hence to rebel against), her decision to continue to "behave" was largely driven by a desire to simply head where the action was.