Nadalind is probably the most accidentally red-stringed fictional couple Iāve ever seen. Way before they were intended to become love interests, the narrative kept connecting and intertwining them (starting with the very first episode):Ā
Nick was the first Grimm she ever saw, and Adalindās was the first woge he ever saw
Adalind was ordered to kill Nickās Aunt Marie (1x01)
Nick had to protect her during a murder investigation (1x03)
Adalind was ordered to date and use Nickās friend and partner Hankās life as leverage for one of the Keys ā
Adalind was forced to consume Nickās bloodāin a physically intimate way (1x17) ā
She put his girlfriend in a magical coma (1x22)
Nickās mother, Kelly, ākilledā Adalindās mother in a fight (really, Catherine just lost that fight) (2x02)
Adalind was protected by and slightly bonded withāunbeknown to both at the timeāNickās mother
Kellyās time with Adalind and her daughter, Diana, triggered her last memory with young NickĀ
Kelly, still unaware of their history, brought Adalind and Diana to Nickās house (3x17) ->
āMaybe itās not a coincidence that you brought Adalind and her baby back here to Nick. [...] Carl Jung, synchronicity [the epās title]. When two or more events arenāt necessarily causally related but are connected through meaning.ā (Juliette)
Kelly let Diana keep her locket with young Nickās picture (3x18)Ā
Nickās mom temporarily raised Adalindās daughter
Nick and Adalind each depowered the other/took each otherās supernatural identity away, temporarily (1x17, 3x22) ->
and both for sympathetic reasons related to the otherāNick, to save Hank from Adalindās spell; Adalind, to get her daughter back from the Royals, who Nick and the others let her believe Diana was with
Adalind was able to do so because of having Nickās blood in her system from when he did so
Bonus: Nickās Aunt Marie had been in a relationship with a Wesen, before she ended it to raise Nick. So the idea and recent precedent of romance between Grimm and Wesen(-related beings) had already been canonized, and with Nickās own relative.