Urban Dictionary - BROTP: Similar to OTP, this refers to a set of best friends in a show, book or movie who are destined to be best friends forever.
(Yep, had to look this one up also)
When I looked up BROTP in the dictionary my choice was clear
Aragorn and Boromir
What would have happened if Boromir had lived? I have to think that he would have been a loyal friend and companion to Aragorn on their quest. The sons of Gondor would have come home together
Sean Bean and Viggo Mortensen are friends in real life as well
Some photos thanks to Empire Magazine