I’ve seen some people discussing what Virgil’s purple eye shadow represents, so here’s my take:
From what we’ve seen in canon, Virgil’s eye shadow intensifies the more anxious he is, as a visual indicator for how hard his core function is “kicking in” at any particular moment. But when we’ve seen this happen in the past, it’s always been anxiety tied to negative emotions. In the end card, while he’s still visibly keyed up, it’s due to a flood of positive emotions rather than fear or distress.
So it’s not that we’ve never seen Virgil truly happy on camera before; it’s just that in the past, we’ve only seen him happy/smiling in moments when he’s fairly calm, and his influence as Anxiety is less pronounced. So it’s really cool to see not just a different side of Virgil, but a different side of Anxiety: instead of prompting fear, it’s powering a figurative runner’s high: the fluttery, adrenaline-rush, oh-my-gosh-I-can’t-believe-that-just-happened feeling.
I just really like the idea that Anxiety’s influence doesn’t have to be muted in order for Thomas to feel happy—that Virgil can be up to eleven in moments of joy as well as turmoil.