Recently I was talking to someone about how much I enjoy the dichotomy of songs that sound light and fun, but which have very dark lyrics. This is something of a specialty of my favourite band, and never have Metric taken it to such an extreme as in Lost Kitten from the Synthetica album.
This is a sugar-sweet, bouncy, bubblegum pop song… with some of the most depressing lyrics you’ll ever hear.
I don’t know if Metric has even explained the meaning behind the song. My interpretation has always been that it’s sung from the perspective of a man who’s fallen in love with a substance-abusing sex worker. She’s too lost in her self-destruction for them to ever be together, but he can’t let her go, so he’s become her enabler.
I’ve heard other interpretations that are far less sympathetic to the viewpoint character, however.
Superior Realities 
I was really hoping that was going to be a song about an actual kitten that actually got lost. So much for that. It’s got about as much to do with a kitten as Angelica’s Why Did You Let My Kitten Die?, another bouncy, upbeat song with a dark, eliptical, worrying lyric invoking images of abuse and control.
As to what either of them are “about”, exactly, good luck working that out. I read the reddit thread where people go into incredible detail, twisting themselves into knots, trying to parse the lyric line by line. It’s an object lesson in the Intentional Fallacy.
There’s so much more power in both because of their inscrutability, of course. The Metric one is the more impressionistic but not by much. And the official video with the guy looking for his mother (Not the lyric one in the post.) really doesn’t help. The opposite in fact.
One thing I would venture: the line that goes “I was looking for a hooker when I found you”. I’d bet it’s an intentional nod towards The Human League’s “Don’t You Want Me?” which brings in all kinds of meta-referentialities.
Good song, anyway, whatever it’s about. Thanks for sharing!