Help, identifying these bedroom ceiling wires

[RManchester]

I'm in the process of pulling the original 2003 bedroom roof vent and replacing it with roof fan. I'm in no hurry and want to do the job right like all of you would. I had planned on pulling power from our bedroom lights wires and drill a small hole through one of the ribs/supports. but have found these wires stuck in the celling area next to the vent and thought they might be a better choice. I have looked at the owners manual and "purple" supplies to BDRM,BATH FAN,COMP,LTS I'm not sure of the color of the other wire? is it yellow? or is it a ground? Yes, I can poke a hole in it and test it, but I would rather ask one of you. IF they are both hot wires do I drill a small hole in the frame and get my ground from it? Next question, have any of you tried the Posi-Lock connectors to tap into a wire. (they look better then the old school connectors)

[RManchester]

If anyone stumbles across this post while installing a bedroom vent fan and finds these wires located front side of the roof vent glued to the aluminum skin and insulation. I went back out this morning with a rag and kerosene and cleaned the wires. The gray and purple is now solid purple and the yellow wire looks white. Perfect place to pull power and ground for the fantastic-fan.

[RManchester]