The only scenes we got wherein Viktor actually expressed any emotions were the scenes in the cosmos. On the ground, within his Herald Era, he always has the same expression: calm, tired eyes, eyebrows slightly furrowed, mouth thinned.
Meanwhile, in the cosmos, we see him actually reacting to the things he comes into contact with: Vanders soul, Jayce's actions, etc. Look at him: his wide-eyed wonder, his almost childlike, innocent curiosity, his search for answers.
THAT is Viktor. This is him as we knew him in s1 act I, where he and Jayce figured out hextech. Where they levitated. Where they explored and discovered. And his eyes! Theyre gold! Those are Viktors eyes!
Maybe, without his deteriorating physical body to hold him back, Viktor can finally focus on that which he always loves: science.
"Scientists seek discoveries", and he still does!
Yes, his mind-body-soul-heart connection was, well lets say muddled at best (which does bring up my fav philosophical question of "where does the [sense of] self end?", but that aside), but he was still There, at least in some form.
