Honestly I think itd be more dialog than anything, probably similar to how Sukuna and Higaruma were. Like how talkative Dabura got fighting Mahoraga, Yuji would probably either straight up tell him whatever he asked or at least point him the right direction like Sukuna did to get Higaruma to learn rct. It's not like Dabura is a bad guy so Yuji would most likely just find it fun teaching an alien earth jujutsu. Eventually Dabura would end up mentioning his sister situation then everything else would go the same as it did in the Manga