I haven't actually listened to Spar yet, but I read it a while back. It's interesting to see so many takes on it. The main thing that struck me was the alienation of intimacy with someone you don't understand and who doesn't understand you... I always thought that's why the bit with the poems was there. She tries to tell her boyfriend that's not what she wants or likes, but he keeps on with it anyway, trying to make that connection. That and the part where she touches something inside the alien that actually hurts it, the only thing that ever gets a change or a reaction, and she spends her time hunting for that spot but never finds it again. When I read it, I sort of got the idea of the alien as an extrapolation of the parts of other people you don't understand. You still have to share space with people, sometimes you even try to make that intimacy happen, but so many times, it's a miss, you know? You don't know what they want and they can't seem to tell you, and you hurt each other, or make each other miserable, or just do something that feels empty and meaningless, because you don't know how to bridge that gap.
Anyway, that's what I got out of Spar. A parable about terrible relationships.
Thanks to Scattercat for posting the interview link. I'ma go read that now.