Conversation so far:
What is the origin of Pierrot?
Pierrot's origins among the Italian players in France are most unambiguously traced to Molière's character, the lovelorn peasant Pierrot, in Don Juan, or The Stone Guest (1665).
Was Pierrot a liked character?
The naive and appealing Pierrot became tremendously popular in French pantomimes.
What French play did Pierrot first appear in?
Pierrot's origins among the Italian players in France are most unambiguously traced to Molière's character, the lovelorn peasant Pierrot, in Don Juan, or The Stone Guest (1665).

Question: In Don Juan was Pierrot an antagonist?
Self-contained rewrite: In Don Juan, or The Stone Guest was Pierrot an antagonist?