Answer:
The prince is his close relative and unlikely to punish him with death.
Step-by-step explanation:
The scene of "Romeo and Juliet" by William Shakespeare opens with a quarrel between Tybalt, a Capulet and Mercutio, a very good friend of Romeo Montague and also a relative of the Prince. The two families of Capulet and Montague had been at loggerheads for a long time.
Later, in Act 3 scene i, we find Mercutio and Tybalt fighting, eventually killing Mercutio. The Prince had given the decree in Act I scene i of no public duels which was emphasized again by Romeo in Act 3 scene i when he tried to break up their fight. But he knows that since he is a relative of the Prince, he might be saved from the decree. So, Mercutio wasn't afraid to fight Tybalt when the latter abused Romeo.