Two characters, one big one small [or shifters], that start out incredibly untrusting and anxious of each other's intentions and pasts. But then over time, despite each of their flaws, they show that deep down they are both good people that want to care and trust for someone.
They start showing little bits of this through tiny gestures.
The giant respecting that the tiny has anxieties about being picked up without warning.
The Tiny noticing the nervous way the giant looks at them, and how they lower their voice when speaking to avoid scaring them or seeming overpowering. The tiny then, against their better judgement, giving them a gentle touch to their retracted hand for the first time.
The tiny falling asleep near the giant for the first time ever, despite their powerful anxiety about being vulnerable.
The giant [shifter] expending all their energy in protecting the tiny, and then collapsing, exhausted and shrunken down, trusting the tiny with them in their most powerless state.
The tiny going out of their way to hang out with the giant for no reason.
The slow disappearance of the tiny's jumps and flinches whenever the giant steps or sits down near them, or when they laugh a little 'too' loudly. They start to laugh along with them.
All the little things add up... and one day when they're sitting side by side, or with one in hand... or perhaps after some life-threatening event where they saved each other and are beaten up, but alive because of the other... they can't imagine why they ever distrusted each other.