Fluffy can not see or hear much, she navigates mostly by smell and responds defensively to new or changing smells.
You might witness Fluffy contorting to lick her own back leaving a frothy residue in her quills. This is called 'anointing'. It looks strange, but it is perfectly natural. We're not sure why hedgehogs anoint. Our favourite theory is that she likes to collect smells and rub them onto herself as a disguise against potential predators following her scent.
Hedgehogs defend themselves by realigning their quills into all directions and sometimes also curling up into a ball, where they are covered entirely in spikes. This is accompanied by 'huffing' where the hedgehog hisses and jerks in an attempt to scare off any threats. Huffing can force quilts into anything touching the hedgehogs, be careful not to put your hand too close.
Instinctive curling and huffing is important so that hedgehogs can defend themselves even while they are sleeping. Do not be offended by it, even if you have bonded with the hedgehog previously.
Some hedgehogs can sit inside their own skin, with their front exposed through an opening in their 'ball' position, and look quite peaceful. Fluffy is not one of these hedgehogs, she does not like to sit still and will flip in an attempt to realign herself with the ground (or whatever surface is available).
Fluffy can swim but is not confident or comfortable doing so. She is better left in shallow water so that she can paddle. See bathing for more advice.