Hey there. Makes me curious about the image you're referencing… :D
Anyway, I've come up with a few ideas for names.
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Angel Wings and Deadly Things - references the plot and both the characters along with the contrast between them, plus has a rhyme to it
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Angels and Dangers – similar to before but shorter and, possibly, catchier
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Halo, Hello, Hell no – a possibly amusing way to summarize the premise if it's not too serious
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Wrong Lane (or Wrong Lain) – a metaphor for living a dangerous life (“going down a dangerous path”/”going in the wrong direction”) which can be also be a pun if the bad girl's name/surname is Lain/Lane, might work even better if the bad girl drives a car or if driving plays a somewhat significant role in the story
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Tempting Fate – references fate and temptation, can be taken in different ways...
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Date with Destiny – similar to before, has “date” which can imply romance
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Fighting Fate / Defying Destiny / Destiny Deviance – variations of alliterations, the last one can be seen as referencing deviation from norms
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Downward Spiral – references the life of the bad girl, also, a Nine Inch Nails reference which might be cool
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Under My Wing – can be seen to represent different things: literal wings, protection and physical contact
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168 hours – references the week but makes it more intense because time passes even when you sleep
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Our 168 hours – like before but also mentions the connection between the girls
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See you tomorrow? – references that there may be no tomorrow and the connection between the girls
I hope this helps.