I don't much like Tendou and I think the "really bad background" story is a bit cheap, really. As far as I can tell in real life most consistently nasty selfish people do not come from abusive backgrounds; rather, they're more likely to be spoilt, while some are just jerks because, you know, they're jerks. People who come from abusive backgrounds can be screwed up for sure, just . . . not usually quite that way, I think?
But I'm not majorly peeved about it or anything. I was more or less expecting it, and it's likely to be fairly well executed so, whatever.