Jeff, has this oscar always been by himself? If so, trying to add something at this point may or may not work out. I keep an oscar and a severum in my 75g, but they were added together when they were not much bigger than a US quarter. The severum is the bossier fish by far. It's worked for me for ~3yrs so far, but is a combo that may not work for everyone. I can keep nitrates <20ppm between WWCs,but space is limited for these 2 fish in a 48"x18" footprint.
I get no drama or pouting out of my oscar, because each fish is more concerned about what the other is doing and that the other one isn't getting all the food, etc. I could drop any fish worthy food in the tank and they'll blow through it just so the other one can't get it.