Yikes!! Loaded question!! (cut for length)
I think it started just with them being two cute girls that I thought complimented and contrasted each other really well. But then the chatlog where Jade tells Rose about her mom happened, and there was a true dynamic to them that to me showed a great relationship. I am convinced Jade is the only one Rose could’ve had that conversation with. It had to be Jade, and it’s a good thing it was Jade.
From there, it’s a fire that’s been fed by friend and fellow shipper alike. There’s enough there about the two of them to play with in canon, but also enough space to breathe and just have a lot of fun with the pairing.
Exhibits A through H:
I rest my case.