Not to derail the topic but our AfRock (baby bout 3.5') acts very similar - always looking to hook that prehensile tail around something and get a coil or two around for anchorage. She is never still either (unless she works her way under your shirt on your shoulders - she will just "grind" away then) but doesnt seem to mind hanging headfirst so she can lift that 3/4 of her body and point it at the next nearest person. Extremely different from the balls, who even when exploring have a very cautious deliberate pace by comparison. Much like your BCI Will, folks are reluctant to hold something that active.