I do think it's maybe the sweetest thing I've ever seen that Pantalone lets Dottore love him exactly how he naturally loves people. He lets him experiment on him, vivisect him, treat him more like a multi-faceted object than a person at times, but he doesn't let Dottore control him, and Dottore doesn't push to. Want me to stop smoking? Fuck you I paid for these lungs. Wanna use my soul to make your next homunculus? Do you actually think that would feasibly work in practice, dipshit. This is a man who has spent centuries being codependant on Teyvat's worst guy and is completely numb to his shenanigans. And somehow... their dynamic works?
"What's a little discomfort between family" is exactly how he treats Pantalone, just like Columbina said. But unlike Columbina, or literally anyone else on the planet, Pantalone doesn't fear him. He fully accepts that that's just Dottore, and flaw or not he doesn't care to try and change it. And he knows when and where to draw the line between "Dottore being dottore" and "Dottore being a freak", and Dottore respects that, and respects him for doing that.
It's a strangely realistic depiction of love, actually. Love like that isn't all bliss, it's a lot of discomfort, a lot of labor and indulgence of the other person. In some ways, it's like a transaction. Maybe that's how Pantalone thinks of it. Because no matter how much he gives Dottore, he does get it back. He gets back the investments he makes into his research, the experimentation on his own body in the form of bleeding-edge healthcare only he is privy to, the company of a partner who truly and fully understands him. This isn't a kind of love you dream about, but it's a kind of love you very well could have and hold.
To put it simply in the words of Whizzer and Marvin from Falsettos;
