First the Flash season 3 finale
While a new threat that Kreisberg and other CW officials claim to be greater than Flashpoint but certainly not bigger than Savitar regarding Doctor Alchemy's final husk, the big thing about this episode is where Barry is about to suffer another or maybe his biggest loss of people close to him at the hands of his most powerful nemisis, Savitar. The only question is who is the evil speed god going to kill?
Jay Garrick for his speed just because he was seen falling down many stories off a building in the trailer?
Maybe but the time remnant of Barry shown in the beginning of the 55th episode's promo would say otherwise and who the remnant that Barry is teaming up with against Savitar is very much likely to be the one of him bringing Jay into Earth 1 from Earth 3 hinting that he will travel back in time to save Jay and rethink his stradegy which would lead to Savitar here in the Arrowverse killing the one person that Barry loves most to rob him of the pride that kept him from killing Zoom for his father's murder
Iris
I know, harsh and it would definatly be the most heartbreaking loss for Barry but because Thawne killed his mother, Zoom (unmasked as Hunter Zolomon) killed his father, and with Savitar being faster than any speedster he came face to face with and capable of controling motion of anything and causing tremors and earthquakes (even for a god depicted in the Arrowverse as Megatron) he is very much likely to kill Iris instead of sparing her and this scene of him kidnapping and holding her captive is not likely to be the same as Barry's nightmares of Patty being killed by Zoom. Especially with Barry having changed the timeline that the ramifications are too great for her fate to be a dream or with her put into a shock. And since Barry had Eobard help him restore the timeline with the leaks of tensions making it end up a paradox all because creating Flashpoint just to save his parents and have a much more safer and normal life with them got Wally killed by Rival and everyone else pay for his happiness, Barry wouldn't bring Jay into Earth 1 to help him fight Savitar just to get him killed because if he doesn't travel back in time to erase his death to save him, everyone on Earth 3 will again be at the mercy Garrick's enemies again after Team Flash freed him from the cell Zoom held him prisoner in for so long. Which is why Iris is more likely to end up killed by Savitar for real instead of in a dream and once he does kill her by dropping her off a tall building leaving her die in Barry's arms at terminal velocity or with the speed god impaling her infront of Barry in the park.
And for poor Barry, knowing that he will cry and mourn over her death at a much greater magnitude than his parents, he is gonna cope with his next loss by either turning himself in as shown in a possible future of the timeline in season 1's finale or by leaving Central City and going into exile somewhere where he won't be found without leaving anything of his behind for Cisco to vibe his current location so that he can try to forget about all the horrors that the three hostile speedsters have put him through until either at somepoint during the midseason 3 premier episode or until the musical crossover where he reunites with Supergirl a third time rather than traveling back in time to prevent it since he has learned by now that consequenses from time traveling cannot be suppressed. But for Wally, he is more likely to retaliate against Savitar for murdering his sister but even if he does face the speed god who restored him his speed, he won't beat him but if Savitar over powers him and spares him just to explain his actions, Caitlin may have to prove to Wally with her abilities why he shouldn't get so worked up out of grief. Joe however may come to regret not helping Harrison Wells talk Barry out of bringing Zoom into their earth since it's what made Barry put everyone in the mess they are in because of his fears, pride, and emotions being difficult for him to embrace. Why should Iris die intead of Jay? So that Barry won't be to stubborn with his pride and succumb to his fears again that made him cause many people close to him die by the worst of his enemies like Zoom and then he will be more optimistic and more of a serious hero than he was from the beginning. That way he'll be able to think smarter next time before he asserts himself into doing something he'll regret and not hesitate from saving anyone out of fear so much.
Now for the Arrow Midseason 5 finale where Green Arrow and Prometheus finally come face to face;
Throughout the previous episodes of season 5 Prometheus was desperate at making sure nobody including Tobias Church kills the Green Arrow showing that he definately knows Oliver is the emerald archer himself. After Felicity traced some of the weapons used by Prometheus back to the SCPD lock up they suspect that he was a cop, but their speculation appeared to be off when Quentin proved to us that he was certainly not Prometheus because he told Thea about the blood wound on his wrist and showed her the star that he found in his apartment after he woke up from a hangover a week ago leaving Oliver to suspect that Prometheus knows that he is the Green Arrow after hearing about Quentin meaning that Prometheus knows about Felicity and her high level hacking skills and intellect as well. And now that we learned from the promo to the midseason 5 episode that the reason Prometheus doesn't want him killing the Green Arrow is not so that he kills him but to make him pay for letting his pride get alot of innocent people in Starling City killed in the past 3 seasons of the show and there is one person who is most accurate on being revealed as the true identity of the throwing star killer Prometheus, someone that knows him too well as the Green Arrow to end up being anybody else in the show and obviously knows about all of Oliver's friends and family as well. It is none other than Oliver Queen's best friend who died in the first season finale;
Thomas "Tommy" Merlyn!
Now before the how and whys, here is what proves that Colin Donnell would reprise his role next week on Arrow that his character Tommy Merlyn is Prometheus and how he came back from the dead by his father Malcolm and why he as the villain would be someone Oliver created. And why he would want to make Green Arrow suffer for his pride.
1. Laurel Lance - Tommy gave his life to save her in the season 1 finale but now because of Oliver for letting his pride delude him into being stubborn to Lance by not listen to him on what Damien Darhk was capable of which led Oliver into getting his daughter killed by Darhk making his sacrifice be for nothing and because Oliver's pride made him too careless to think of the consequences of revealing himself to the crowd of people in season 3 after winning a war against criminals led by Brick he ended up getting the mayor from that season along with others killed by Ra's and the League of Assassins which is a good explaination to why he wants to destroy Oliver's pride by making him suffer by having his allies attacked.
2. Flashpoint - Because of how Barry's actions on tampering the timeline would have a major effect on Arrow, having Tommy's resurrection by his father Malcolm would serve as the primary example of how much Flashpoint affects the series and not just cheap parlor tricks like replacing baby Sara with baby John or with Oliver going crazy in front of his sister as well as having corrupt cops in the SCPD.
3. Artimis - Because Tommy back in season 1 helped Laurel and Oliver protect an innocent little boy from an evil and selfish assassin Mr. Blank who murdered his parents, Artimis, whose parents were killed by Ruve Darhk, would easily remind Tommy of that boy which is one good reason why he would enlist her as his spy in Team Arrow and as his protege.
4. Donnell's character was the Merlyn from DC's New 52/The Prime Earth Green Arrow comics. Even though it is confirmed that Prometheus won't be based on any characters from the DC comics, it doesn't mean his identity can't be anyone from the comics because where would the fun in that be. Besides, Rocksteady wasn't being 100% accurate on their statement of the Arkham Knight from Batman Arkham Knight being an original character
5. The midseason 5 finale episode's title "What We Leave Behind" Hints Tommy Merlyn's return and resurrection
6. The List: Since Prometheus killed Tobias Church after the big man himself blew his last chance to stand down from threatening the Green Arrow, he's been targeting people who's names we're left on the list showing that he is someone that knows Oliver has been keeping a booklet of people who left Starling City in a heap of crime best since the best in the first season while dealing with Malcolm Merlyn, even if Artimis told him about the list, it's only because he knew about it which is another good reason why Tommy Merlyn is Prometheus resurrected by his father to know about the names of the people he's targeting on the list.
7. The Steelmill, since Prometheus has been using the steelmill to forge some of the arrows and other resources from the SCPD lockup into weapons of his own, he has to have worked and hung out at the place since the beginning to have access to the machinery and equipment to make the weapons
8. Vigilante is assumed to be working with Prometheus since Artimis was revealed to be working for him as a spy that Vigilante's comment about her condition was a bluff and since he is district attorney Adrien Chase he would have access to the SCPD lockup and with help from some of the cops that are in league with him, he would not only have gotten his hands on some of the weapons he uses to kill criminals but also since he is working with Prometheus and Artimis, he has to be the one providing them with the resources from the SCPD lockup showing that Oliver's new arch adversary has more help backing up his campaign against him.
9. His threats on Tobias Church to not and not let anyone kill the Green Arrow showed how potential he is that Prometheus knows him as Oliver Queen way back in season 1 and how he knows how to deceive him when it comes to throwing off his team's suspicion as well as coming prepared with help from allies
and finally
10. Weapons and Combat Skills: Since Prometheus managed to subdue and slaughter all the cops escorting Tobias Church before killing the latter himself showing that he is quick on his reflexes. He also uses a katanna and a battle axe and is very well trained at hitting his targets directly with his bow and arrows and hurling his battle axes and steel stars directly at his targets from any direction. Now how would Colin Donnell reprise his role as Tommy Merlyn so that his character would be resurrected and revealed as the true identity of Prometheus since he is still working on a series regular role in Chicago Med? Since Prometheus is a fully costumed supervillain here on Arrow, it is possible that a stunt double is doing most of the acting and that Donnell would have just enough time to act out his scenes as Prometheus revealing himself to Oliver, berating him for his pride and before taking him on in an epic fight. Plus after seeing how potential Prometheus is for his grudge against the Green Arrow and for how he knows him and his friends so well, Tommy Merlyn is the perfect fit to be Prometheus' true identity and way too good a fit for CW officials to pass over anyone else. Which is why they shouldn't make Prometheus end up being anyone else because then everything on the character would end up being nothing more than a flock of flukes if he ended up as one of these guys and here is why it can't be any of them.
Billy Malone: SCPD detective and Felicity's boyfriend. Even though he works at the SCPD and was told by Felicity that she works with Team Arrow and Prometheus' shadow from next week's episode promo lurking behind him, it doesn't mean that Malone is the throwing star killer because if he was, he would have been someone that knew Oliver along time ago before the start of the series and CW wouldn't tease Prometheus' shadow behind the detective in the promo if he was the villain to spoil his identity too soon. Plus he's helping Felicity discover who Prometheus is.
Quentin Lance: He may have had the same blood wound mark on his right wrist like the one Artimis scarred Prometheus with but it doesn't mean he's the man behind the mask because other than being drunk and out of shape, his career as deputy mayor is too good for him to take advantage of over Laurel's death plus he already confirmed it by telling Thea about the blood on his hands and the steel star he found in his apartment. Besides it wouldn't work well with him antagonizing Oliver And it is certainly not Laurel, Nyssa, Talia, the russians, Roy Harper, Slade, or anyone else in particular. And certainly not the Russians from the season 5 flashbacks either. The past that the link they discover Prometheus' history with Oliver has to be someone that has been around since the begining of the show and whatever they find better be a photos, newspapers, or anything that Oliver and Tommy shared together long time ago. That is why next week on the midseason 5 finale of Arrow that Tommy Merlyn resurrected, heavily armed and trained by his father has to be the true identity of Prometheus. So tune in for next week's midseason finale episodes of Arrow and Flash