I've had Lucy for 5 weeks now, including the week that I was off at the Gordon Conference. Luna and Rugrat are pretty much used to her by now. They gang up on me to get them to feed them, eat from the same bowl and sleep on the same bed, not get too bent out of shape if Lucy runs up to them at full speed or sniffs their butt, and Rugrat and Lucy will play together occasionally.
When I got back from the conference, it seemed like Luna and Rugrat were less clingy than they usually are after I travel. What's more, it seemed like they had bonded in my absence.
I think they have benefitted from having a buddy. Rugrat is a lot less bored, and has stopped watching TV in favor of watching Lucy. That is good - although soccer games are good healthy entertainment for a cat, I can't say the same about "The Real Housewives of New Jersey." Luna is more active now, and her digestive issues and eczema have cleared up.
Lucy is a very high energy cat, and is fond of racing around the house at full speed, doing the spiderman walk along the sides of my bed, playing with her cat toys, jumping up in the air, chasing flies, play fighting with me, and going outside. All this exercise has left her a lot more muscular than when I first got her. She's pretty smart, and has figured out how to open the screen door quickly, no matter how tightly I shut it. She is affectionate, and will lick my hands when I am petting her or sleep next to me, but is not a total snuggle fiend like Rugrat.
I am very glad that I got her.