Theres three ways(from what i know):
1.) You eat something before seeing Pierrots show, then some stuff happens(i won't say because I don't wanna spoil) But anyways! Sooner or later in that route You'll see Harlequin. You need to be quiet and silent and not scream.
2.) You don't eat before seeing Pierrots show and then call it scary. He'll then ask to see you again tomorrow and if you say no, something(close to 1.) will happens. Its mostly the same as 1.) Only that theres another way of it happening. So yet again, stay quiet.
3.) You say you secretly enjoyed Harlequin's company in his tent after his show. You then don't eat anything before Pierrot's show and say it was amazing or fun. Sooner you say you'll meet him tomorrow and he leaves you a alone(for a bit). After that theres a dialouge about You talking out loud and Harlequin hearing and then he asks you to follow him. If you say yes some stuff will happen. (For the last time now, I won't spoil so much.)
I personally think that 3.) is the most fun one to chose but its my own opinion! I hope this helps!