Exclusive: Actor Matthew Gray Gubler appears in Will's funeral in Criminal Minds: Evolution season 3, episode 3.

JJ actress A.J. Cook spoke to Screen Rant in an exclusive interview in which she addresses what it was like to work with Gubler again after so many years. Cook revealed that not only did she personally reach out to ask him to be in the funeral episode, but she spoke glowingly about reuniting with Gubler. Check out the interview below:

Screen Rant: We saw Spencer return briefly this episode, which was wonderful, but it's been a few years since you've acted with Matthew Gray Gubler. Did you find it was like picking up right where you left off, or was there any rust?

Cook: No, that's like riding a bike. I was just so happy to have him there. The fact that I called him and was like, "Hey, this is what's happening. It would just feel really weird if Spence wasn't there." And he was like, "Absolutely, I'll be there." So the fact that he came and showed up for us and for his friend just felt like a homecoming. Loved having him on set, and I'm so grateful that he decided to come and play with us again.

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Cook Loved Having Gubler Back On Set

Spencer Reid's absence was always left open-ended enough that he could be brought back into the action without jumping through any hoops. But if he wasn't brought in to take down Sicarius, it makes sense that it was for something more emotional than investigative. Cook felt Reid's appearance was important on a character level, and it's reassuring to know that Matthew Gray Gubler agreed and made it happen logistically, even if Reid only had one line in this Evolution episode.

Reid's return added a layer of emotional gravitas to Will's funeral. The episode found a way to give his entrance the fanfare viewers wanted without overshadowing the somber nature of the moment. Getting to see Reid's relationship not just with JJ but her two sons (who are also his godsons) was far more emotionally resonant than if he had been brought in simply for his eidetic memory to solve a case.

Cook specifically stated that it would "feel weird" if Reid wasn't there for the funeral, and fans would surely agree, given how special Spencer and JJ's friendship was in the original run of the show. Now, Cook's positive language should give fans hope that Spencer might make more substantive appearances in future seasons of Criminal Minds: Evolution.

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Gubler Seems Open To Returning To Evolution In A Limited Capacity

Fans of an ensemble show always hope that the co-stars are friends off-screen as well, and it's heartening to know that Cook and Gubler acknowledge and respect how important Spencer and JJ's friendship is. Reid’s brief appearance added emotional weight to Will's funeral without being an overbearing distraction.

Criminal Minds: Evolution season 4 in a limited but more meaningful capacity, if the story were powerful enough.