Riveyoelo is Ocelstin's bodyguard and husband. While it may seem odd for a mirror to have a fae bodyguard, he's mostly there for impulse control.
He does not consider Ocel's adoptees to be his children, but loves them anyway.
He is kind, even to strangers, as well as earnest and deathly loyal. He has been called the most loyal force of the Steelwings, and it certainly isn't some one-off thing - he has killed to defend his wife, children, and friends, and will again if the time comes.