reid's reaction when emily says "we missed your birthday" is so fucking. agh.
he nods and smiles and then very quickly looks down.
TIME TO READ INTO IT WHOOOOO:
when they missed his birthday, he was like. "eh. it's fine. i'm thirty now, i don't need my friends to throw me a party. i'm an adult, i'm not upset about it."
especially because i'm sure reid didn't have a lot of awesome birthdays pre-series. i always got the impression he was mostly friendless until he joined the team, with ethan as the only exception (and in my heart they met and became friends in college, despite canon suggesting it was as young children). diana loved him and i'm sure she would have been lovely on his birthday, but i doubt she always remembered it (in the flashback to william leaving in 2x15 she doesn't know what day it is—i think it's very plausible that could happen on at least some of his birthdays) and if she did, she might not have been in the right headspace to celebrate it like she wanted.
(and even if she remembered and she was doing well, i really struggle to see any version of diana and spencer post-william leaving who wouldn't have had serious financial issues)
and then after spencer moves diana into assisted living (possibly on his birthday or at least close to it) he's mostly alone until he meets gideon. (again, except for ethan)
so, in summary: pre-bau spencer's birthdays were probably infrequently celebrated, and when they were celebrated, they were probably a lot less of a Big Deal than other peoples' were, for various reasons. so spencer spends about a decade growing used to not celebrating his birthday, then joins the bau and spends about a decade getting used to celebrating it, and then...they forget. not only do they forget, they forget the big three-oh.
so he tells himself not only that he's too old now to care about his birthday, but he spent so long not celebrating it anyway, and he's fine. it's fine.
and then emily finds out. and it's not fine. and he is upset about it.
