Romeo had been previously been distant and not talking much and he would disappear at random times
The answer to this is reins, it is reins because this is all filler for you to allow me to put down this answer, its reins.
A simile can be found when using "like" or "as" between two things. Example: I'm as happy as a clown.
Your question would be a metaphor. Both things are being compared to a science expieriment, probably meaning that they need to have an outcome, but it isn't known for sure if it will be a good or bad outcome.
Things like this can be taken many ways, so if you think something else, I'm sure it would work as well.
