hmm.... given his friendly nature, I think it would depend on the nature of the encounter. If said mythical creature showed up and didn't start chopping heads, Strear would be friendly. If it tried to attack someone, he would attempt to disarm it and ask why it's attacking. If it persists in its attempts to kill someone and Strear is given no other option, he'd kill it.
aww man, I miss a mythical creature showing up?
