The Marvel Cinematic Universe at this point extends across multiple mediums, with theatrical films, Netflix original series and network TV offerings like Agents of S.H.I.E.L.D. all existing in the same shared continuity with characters able to move back and forth between all three. However, one barrier yet to be crossed is the one between animated and live-action offerings, with both films like Big Hero 6 and cartoons like Ultimate Spider-Man thus far maintaining a distinct separation from the MCU-proper.
But that separation is about to get a little less distinct for Spidey fans: Two fan-favorite characters from Agents of S.H.I.E.L.D. are set to join the extended cast of Ultimate Spider-Man.
Specifically, as part of the latest Ultimate Spider-Man season's ongoing "Sinister Six" storyline, Spider-Man unexpectedly encounters S.H.I.E.L.D. scientists Leo Fitz (Iain De Caestecker) and Jemma Simmons (Elizabeth Henstridge) - who offer him technological information and help on combating his latest threat in much the same way they do for Coulson and company in their live-action incarnations. That said, this version of the buddy-couple popularly known as "Fitz/Simmons" do not appear to be recovering from the same level of baggage afflicting their current live-action counterparts on Agents of S.H.I.E.L.D..
Though by now almost every character (and character-pairing) on Agents of S.H.I.E.L.D. seems to have its own devoted fanbase, Fitz and Simmons were the early breakout faves for many in the show's first season. A pair of excitable, social-awkward scientists gifted with genius and child-like outlook in equal measure, along with acting out the ever-popular trope of two fiercely devoted best friends who've yet to realize that they're also madly in love with each other; audiences attached themselves to "Fitz/Simmons" early on - a phenomenon which Agents' was happy to exploit for added drama by throwing grim barriers in the path of their would-be relationship: Fitz suffered from brain-damage and PTSD as a result of season 1's near-fatal finale, while Simmons spent the time between seasons 2 and 3 surviving by her wits after being marooned on an alien planet.
While not officially part of the Marvel Cinematic Universe shared continuity, Ultimate Spider-Man incorporates more references and similarities to the MCU than most other non-affiliated Marvel animated offerings. The series, which chronicles the exploits of a teenage Spider-Man whose journey to superhero adulthood is being monitored and directed by Nick Fury (and a still-active S.H.I.E.L.D.), features MCU-reminiscent character designs and a version of Agent Phil Coulson acting undercover as Peter Parker's High School principal. So it stands to reason that many of the same supporting characters that exist in the live-action realm would also exist here, if not the same precise versions.
It remains to be seen whether Fitz, Simmons or any of the other Agents of S.H.I.E.L.D. will be making regular appearances on the series; or (or for that matter) if they plan to eventually cross-over into the Cinematic Universe proper officially. The series is expected to intersect with the plot of Captain America: Civil War later this season, and a recurring character typically associated with one of Civil War's main antagonists recently re-emerged as part of the series' midseason return episode; so it's conceivable that the crossover could be more substantial than the one-off reference connecting Age of Ultron. After all, the series' inaugural season was heavily effected by the events of Captain America: The Winter Soldier.
Agents of S.H.I.E.L.D. continues with ‘The Inside Man’ on Tuesday, March 15th at 9pm on ABC. Ultimate Spider-Man airs on Disney XD.