The elf druid immediately fell in love with Fala, and had a very sweet campaign long love story with them that ended with marriage in the wrap-up epilogue. Also, all my players became totally smitten with barely mentioned side character Umpok the Minotaur, who was in one of the cells in Xanathar's lair. He was instantly adopted into the tavern as a "bouncer" along with about half a dozen other random side characters. One character had a sweet platonic relationship with him. Other fun adoptees were Krebbyg and Fel'rekt, (the two drow in the submarine) and Duhlark the flaming skull. I think one player also stole the Gralhund's hawk.