When did he chose Nakul over otherss??
Nearing the end of their 12 years exile, one day the Pandavas (all 4 other than Yudi) got attacked by an Yaksha near a pond from which they were trying to drink water. The Yaksha said repeatedly that they will have to answer his questions first & only then they can drink his pond's water. But the younger 4 Pandavas didn't pay heed to this & tried to drink from the pond without answering Yaksha's questions. So the Yaksha killed them one by one. When Yudhishthir reached the scene & tried to drink water he was told the same thing. Yudhishthir actually answers him first. Being satisfied with Yudhishthir's answers, the Yaksha said he will return one of his brothers life back. Whom would Yudhishthir like to choose? At this, Yudhishthir chose Nakul on the logic that he himself was Kunti putra & was alive. One Madri putra needs to be alive too. So he can't choose Bheem or Arjun & he chooses Nakul.
It appears that the Yaksha was actually Lord Yama in disguise & he was just testing Yudhishthir. Being pleased with Yudhishthir's choice, he returned all the Pandavas back to life.
I think SP MB has also showed this. Though they messed up the timeline & showed this to be the first important event in their exile😆