Fair, I wasn't intending to list the entire ISA as Ensemble Darkhorses but note that, while as a whole they're well-received, there's been special positive attention to the minor characters. I realise looking at it that the wording was probably not the most clear.
If you guys feel they're ensemble dark horses or it's a wasted plot, that's good enough for me. People on this site are often ridiculously arbitrary.
Isaac Bowin's death without finding out more about his mom's death has been posted twice (by me and a different person) as They Wasted a Perfectly Good Plot and both times the same person has yanked it while talking about how implausible the circumstances were for that to happen anyway. It's possible that trope is perfectly justified in saying that, but I feel that the topic warrants a discussion.
Even when something is unlikely, if it's possibly, then if multiple people wish it had been done then by default it could arguably be considered an example of They Wasted a Perfectly Good Plot.
Sportscaster and Tigress are Ensemble Darkhorse characters who already broke out of jail once and easily could have done so again especially if they think Artemis is in danger from Eclipso, so I'm skeptical about the ascertain that their current absence form the story completely precluded any chance of Isaac finding out they killed his mom.
Dragon Master 408 also doubt the likelihood that Isaac would believe the JSA over Cindy if they denied it. I disagree, given how Cindy is an Obviously Evil Alpha Bitch who wasn't exactly best friends with Isaac until she needed him as an accomplice.
Finally, since it's a bit vague how deep Eclipso's telepathic abilities go (at least in the show), it doesn't feel completely implausible he could have found out somehow while Sportsmaster and Tigress were in town and then used that yo taunt Isaac (although that may be a stretch).
Re: The Injustice League being Ensemble Dark Horse. As it is the case that they are the villains I don't think they would normally be eligible for the trope, but if any of them are considered guest characters then that's good enough for me. Though they should be listed as their own examples rather than saying the entire League since Icicle is still the Big Bad and definitely isn't EDH material.
You fell victim to one of the classic blunders! Hide / Show Replies