[SPOILERS for those not caught up on Agents of S.H.I.E.L.D. ahead.]
Agents of S.H.I.E.L.D. first teased the introduction of Life-Model Decoys or LMDs to its corner of the Marvel Cinematic Universe during its season 3 finale - with a credits "stinger" that showed (slightly mad) scientist Holden Radcliffe (John Hannah) working on a mysterious project titled, quite simply, LMD. The concept of LMDs comes straight from the world of Marvel Comics - but as is typically the case when comic book elements are introduced on the TV show (see season 4's Ghost Rider storyline, for the most recent case in point), S.H.I.E.L.D.'s showrunners Maurissa Tancharoen and Jed Whedon are putting their own spin on the concept and making it better suited for the MCU.
The subplot concerning Radcliffe and the LMD Aida (Mallory Jansen) was very much a secondary concern behind the Ghost Rider story thread, for the majority of the first half of Agents of S.H.I.E.L.D.'s ongoing fourth season. That changed in the episode ‘Deals with Our Devils’ - when Radcliffe and Agent May had Aida read the mysterious supernatural book that is the Darkhold, in order to uncover how to rescue Agents Coulson and Fitz (as well as Robbie Reyes/Ghost Rider), from the spot between dimensions where they were trapped. As one would expect however, there will be - and already have been - consequences for that well-intentioned, but rash decision on Radcliffe and May's part.
Agents of S.H.I.E.L.D. began to explore the fallout of Aida reading the Darkhold in the midseason finale, 'The Laws of Inferno Dynamics', revealing that Aida has now created a LMD version of May (Ming-Na Wen) and killed another S.H.I.E.L.D. agent. The above promo for the second half of S.H.I.E.L.D. season 4 further confirms that Aida will be the main threat on the show when it resumes in 2017 - as does the poster for the second half of season 4 (see below), now fittingly dubbed Agents of S.H.I.E.L.D.: LMD.
Whedon had the following to offer the press (including IGN), with regard to why S.H.I.E.L.D. is exploring a storyline about LMDs:
“Reality and identity and trust is always an issue in a spy organization, and it's much worse when you don't know if the person next to you is the person next to you. So you know, obviously we want to not just tell stories of scary stories of things popping out of closets but emotional stories and when you get into trust that's when things get emotional.”
The first season of HBO's new hit TV show Westworld got a fair amount of mileage out of the concept that anyone on the show could be a "robot in disguise". S.H.I.E.L.D. has now pulled the rug out from beneath its viewers' feet once in that respect, with the reveal about May at the end of 'The Law of Inferno Dynamics'. Whedon indicated that the show will continue to explore that notion and its storytelling possibilities throughout the second half of S.H.I.E.L.D. season 4 - though at the same time, he offered assurances that the Aida storyline isn't simply going to be a variation on similar ideas about A.I.-gone-wrong that were explored in his own brother's MCU film, Avengers: Age of Ultron:
“We said it at the beginning of the season that [LMDs] were mimicking human behavior. But Aida took some sort of leap and built a brain of her own and so the real difference is that they represent people that we know and it's not a big robot baddie, and there is some of that obviously, but right now we know that there's one among us who is someone we know. And how much they know and how much their agenda is mixed with their own emotions and those sort of questions are what we're going to dive into."
Speaking of LMDs whose agendas may be "mixed with their own emotions": Phil Coulson himself, Clark Gregg had previously hinted that Agents of S.H.I.E.L.D. would be exploring a romantic relationship between Coulson and (Melinda) May in season 4 - though it's safe to say most fans didn't take that to mean a relationship between Coulson and an LMD version of May. Nevertheless, the S.H.I.E.L.D. midseason finale indicated that will indeed be a part of the LMD narrative when the show returns.
'The Law of Inferno Dynamics' may have laid the foundation for 'Philinda' to be explored (in some sense) when Agents of S.H.I.E.L.D. season 4 resumes, but it also raised new questions in the process. The matter of how much the LMD version of May's future interactions with Coulson are going to be informed by her "agenda" and how much will they be influenced by the LMD's emotions - and how reflective those emotions are of how the real May feels about Coulson - is certainly intriguing and should make for some compelling drama, if handled well. Whedon, as you would expect, was coy about those topics when he was interviewed, simply teasing the following:
“I feel like for the actors and for the characters and for the fans we need to explore [a Coulson/May relationship] and so in some form or another, it'll be a thing."
Agents of S.H.I.E.L.D. season 4 continues on Tuesday, January 10th, 2017 on ABC.