Bolin first met Opal when he was visiting Zaofu along with the rest of Team Avatar. Opal blushed upon meeting Bolin and even accidentally introduced her name after it was already stated. Bolin initially was not sure if he was really interested but Mako encouraged him to go for it. Bolin went to hit on Opal but was not acting like himself which freaked Opal out. He quickly apologized and Opal told him to just be himself. They shared a moment together before Korra came and interrupted them.
The next day, Bolin was afraid to learn how to metalbend but Opal encouraged him to try to learn. Opal later decided to join the new Air Nation at the Northern Air Temple which Bolin supported. Later, when Korra was telling Tenzin about her over the radio, Bolin jumped in to talk about how great she is. Before Opal left, Bolin was sad that she was leaving but Opal insisted that they would see each other again.
Eventually, the Red Lotus attacked the Northern Air Temple and held the Air Nation hostage in an effort to get Korra to turn herself in. Bolin knew that Opal was there and was worried about her. While on their way to the Northern Air Temple, Bolin complained to Mako about how worried he was. Later, when Bolin saw Opal, he pushed her mother away to hug her. After Zaheer was captured, Bolin shoved a sock in mouth to silence him and Opal thought that it was funny.
Bolin and Opal started to date at some point over the next three years. However, Bolin later joined with Kuvira and became an Earth Empire soldier while Opal knew the truth about Kuvira's motives. The two saw each other during a conflict in the state of Yi. Bolin was happy to see Opal but she was upset. Bolin initially did not believe that Kuvira was bad. He eventually found out and defected from the Earth Empire, but Opal's entire family was captured and imprisoned.
Bolin and Opal later reunited in Republic City. Despite the fact that Bolin turned on Kuvira, Opal was still mad at him because her family was imprisoned. Bolin tried to throw a picnic for Opal but she was still upset. She decided that the only way for Bolin to redeem himself was to join her and her aunt Lin on a mission to save her family. Bolin joined her and stated that he would do whatever he could to redeem himself because her loves her. Opal's family was eventually rescued and she forgave him. The two later danced together at Varrick and Zhu Li's wedding.
Bopal first became popular as soon as the two met in Zaofu and showed feelings for each other. Four episodes of Book Three were leaked so it was already known that Opal was going to be Bolin's new love interest. The fans had mixed feelings at first due to people still supporting Boleska and other ships involving Bolin. However, support for this pairing ended up growing. Some had an issue with Opal being mad at Bolin during Book Four, but most fans eventually accepted this pairing as endgame.
- In the Book Four Blu-ray commentary, the creators commented that they like to refer to children of Bolin and Opal as "Bopals" and said that they have even made some "Bopals" of their own.