*shapeshifting is something a basilisk will nearly always seek to do in solitude.

an act which temporarily blinds and numbs the creature from the surrounding world - they will be left completely vulnerable to it. defenseless. frozen inside the shell of their old form as organs and cells rearrange.

to shapeshift in front of someone is, therefore, the ultimate show of trust that a basilisk can perform.*

this takes place post story, because there is no way arvo would ever do this at any prior point, because he is Ill and has the Problems. but i like thinking about it