Ati

[Hoid the Former Drifter he/him]

Does Ati have anything to do with Sel, being that his name is also an Aon?

[Honorless he/him]

No, that's just a coincidence.

I wasn't able to find a WoB though, possibly it hasn't been transcribed yet 

[Kingsdaughter613 she/her]

The two things are pronounced differently: 

1: Ati/Ruin pronounced Ah - tee

2: Aon Ati pronounced Ay-tie

Aons have two hard vowels. (Ay-own. (Aon) Ee-nee. (Ene) Ray-oh. (Rao) Eye-ree. (Ire) Etc.)

[Hoid the Former Drifter he/him]

aha (tee).