In Shakespeare's Romeo and Juliet, what does Romeo's quote in Act 3, Scene 1 mean, "Either thou or I, or both, must go with him" (130)?

Romeo says the line to Tybalt, "Either thour or I , or
both, must go with him," immediately after Romeo's best friend, Mercutio, has been slain
by Tybalt who has just returned to the scene of the crime. In order to better understand
Romeo's line, we must first understand it in context.

Immediately
after having stabbed Mercutio, Tybalt turns and runs from the scene. After Benvolio
announces Mercutio's death, Romeo stands dumbfounded, knowing that Mercutio's death is
about to bring a black fate for Romeo as well. When Tybalt returns to the scene, Romeo
knows he will avenge himself on Tybalt for his friend's death, as we see when Romeo
proclaims, "Away to heaven respective lenity, / And fire-eyed fury be my conduct now!
(III.i.124-125). In other words, Romeo is declaring that he is furious and about to act
on his fury. He then tells Tybalt that "Merctio's soul" is "above [their] heads,"
meaning in heaven, and waiting for Tybalt's soul to keep him company (127-129). In other
words, wanting revenge, Romeo is challenging Tybalt. His challenge continues with the
line, "Either thou or I, or both, must go with him" (130).

In the
line, "Either thou or I, or both, must go with him," Romeo is saying that either Tybalt
must go with Mercutio, meaning must die as well as Merutio, or he, himself must die with
Mercutio, meaning that Tybalt will kill Romeo as well. Finally, Romeo also says that the
other option is that they both must die with Mercutio as they both may kill each other.
In other words, Romeo is warning Tybalt that more deaths are about to happen as a result
of Romeo's vengeful dual. Either Romeo will die, Tybalt will die, of they will both
die.