As for trying to tinker with their brains...Fred told me during the hols that they were working on occlumency with Snape, and it wasn't going very well--and maybe that was something related to their being twins, too. So they had switched to Dumbledore for lessons, which was going slightly better, but not good enough.

Ugh. That reminds me I need to pick up on occlumency practise, too.