New character's survival partly depends on how powerful their creator is, and Williamson is a quite big name, so I can see Flatline on long run. Also Robin current arc is deathmatch between killers, it's not fair to judge Flatline because of her act as per the rule of the tournament. I don't quite understand why some fans instantly hate Flatline since she only appeared in 3 issues so far and she didn't do anything wrong except ripping Damian's heart out which is again, deathmatch rule