Perhaps look at an assortment of plum colored carpet samples and see how the fit

you could try painting the whole room (remaining walls) to match the blue in the curtains.... for accent pillows then go blue, white, and purple. Love your ceiling and looks like a cozy space... if stuck with carpet, curtains, and wallpaper, I would take the blue and paint what is remaining and incorporate accent pillows that MOSTLY feature blue and white (little purple). I think the space will be more cohesive from the blue being caried throughout and the couches will be brightened up by incorporating much lighter accent pillows. Looks like you are creating such a cozy designer home theater space!

You have a nice geometric, somewhat masculine look going here. I would play that up. I don't think you need to change the wall or carpet color as they seem to be a nice neutral background. Are they cream? is the purple more plum? and is the blue more of a steel blue/gray? The furniture is chocolate brown? I love the striped pillow on the chair. I would layer a wool steel blue/gray area rug and then play up the blue/plum in the pillows. A wool plaid or blue gray herringbone in a couple of throw pillows (replace a few of the solid color pillows) could help to pull it all together. Kind of like the colors in the picture of this bag. Adding brown leather cording would be a great compliment on the pillows. (Not sure the area rug in front of the TV is adding anything)

anything grey or silver in with yourliving room walls would look awesome you have two babys how cute ya keep your rugs lol