What would Balthazar's reaction be to Romeo and Juliet's death, and all that had happened?
Since Balthasar is Romeo's incredibly loyal servant, he would certainly mourn the death of Romeo, but I'm not sure he would be terribly shocked to learn that Romeo has taken his own life in Juliet's tomb. By the time Friar Lawrence has arrived at the scene, Balthasar has been waiting nearby for about a half an hour. He says that he cannot accompany the Friar to Juliet's resting place because "[His] master knows not but [he is] gone hence, / And fearfully did menace [him] with death / If [he] did stay to look on [Romeo's] intents" (5.3.136-138). So, he continues to believe that Romeo is alive, but it seems unlikely that he would have stayed if he thought Romeo would just go in and say good-bye to Juliet and everything would be fine; he would only stay, I would think, if he suspected that his master, Romeo, might need him for something, that he could somehow be of help. Balthasar thinks that he fell asleep and dreamed of Romeo slaying someone, but it was really the fight between Romeo and Paris that he saw. Thus, Paris's death would likely not come as a surprise either.