Not an Oc but still someone from the hp universe.

May I present to you the bravest Slytherin. Not Snape and not Narcissa. No I'm talking about Regulus Arcturus Black, the youngest Black son, the first hocrux hunter and the first death eater who betrayed the dark lord and fooled him.

The au behind this pic: Regulus had to play in the Gryffindor quidditch team because McGonagall had enough of the house rivalries and decided to switch a few players from each house for one quidditch season. Surprisingly the younger black brother enjoyed the training and the games with the lions. He got along with them and even after his death when Harry Potter came to Hogwarts, teachers and ghost remembered the time when Regulus Black was himself and showed that to everyone.
And when a certain werwolf became a teacher he saw Regulus in his best friend's son.

I really love all of the ideas where Reggie was trying to do the right thing for his friends and his brother. Also I don't know where it come from but jegulus... I ship it. Still I prefer jily but let's be honest, James definitely had a time where he got tired of chasing Lily and asking her out and her constantly rejecting him. And REGULUS AND LILY WHERE FRIENDS AND GOT ALONG WITH EACH OTHER! The same goes for Remus and Reggie.