We rent a DW where our LL allows us to be creative (but not wild), in decorating our homes, and painting as we wish. The BR's in our rental have the engineered wallpaper built into the drywall. I am hoping to surprise my 3 year old who is on vacation with my husband in Ohio for a week, by remodeling his room with all of his Cars2 deco. The walls are an off-white with a floral texture, and the ever-slightest hunter and plum wide-set pinstriping. I'm wanting to paint the room a light grey. Not a sheer grey, almost the shade of when you LIGHTLY sketch with a pencil. I used primer on 2 walls in our master bath(Killz), when we redid that room, and both of those walls peeled. YET, the wall I DIDN'T use primer on, didn't peel at all. So, my question is, I know I will have to double coat the room anyways, but do I really need to prime? I know I've said in my bathroom, I got lucky and some walls w/o primer were fine. But I'm a little worried that I won't get so lucky. Any advice?