It's not necessarily about hitting the reader with big dramatic moments right away. That can feel cheap. The most effective stuff I've read—and tried to write—with Laios builds from his canon voice. He's analytical, he's focused on monster biology, but there's this deep, awkward well of feeling underneath that he just doesn't have the social software to express correctly.
I'd avoid generic 'you' insertions. Frame the emotional scenes around his specific obsessions. Maybe 'you' get injured by a monster, and instead of a standard bedside vigil, he's meticulously describing the creature's attack patterns to you, his notes scattered over your sickbed, while his hands are shaking too much to sketch properly. The emotion is in the blockage, in the way his hyperfocus becomes a funnel for his worry. The reader has to connect the dots between his actions and his heart.
Another angle is through touch, but make it weirdly practical. He might examine a scar on your arm not with romantic reverence, but with the same clinical curiosity he'd give a dragon's scale, except his usual rapid-fire commentary falters. He goes quiet, his finger tracing the old wound, and he just says, 'The healing process must have been inefficient.' His inability to say 'I'm glad you survived' is the point. The frustration of loving someone who speaks in data is the core of the emotion.
You have to be okay with the payoff being subtle. A smile that's more a twitch of the lips, a long, thoughtful look across a campfire while he's supposed to be categorizing the local flora. Let the reader feel the weight of what he doesn't say.