I found these possibilities:

What does a triangle inside a circle symbolize?

~It could be the Triangle of Evocation, created in the days of the Middle Ages, used to call a spirit to appear within it, usually a demon.

~A Thaumaturgic Triangle is a symbol with a triangle and a circle. The movie “Paranormal Activity” featured this symbol. In the movie, the coven used it to summon and, at the same time, control a demon.

~ Navajo peace pipe Mandala depiction – (a circle with two arrows piercing it in a criss cross formation) This looks the least like his tattoo, even though he does look Native.