Does anyone have experience with severums and blood parrots? I read that they're mostly peaceful, but I got one severum that always chases/bullies around a smaller one, and he fights with the blood parrot
A few possibilities could be happening here.
I've had a lot of Heros (severums). They are peaceful, generally, but some individuals are exceptions to this. The problem might be having just the two of them, possibly of the same gender. I've never personally had blood parrots, but from what I've seen sometimes they work with severums, sometimes not. Just two or three fish of similar size, shape, and color can sometimes be a problem-- with no particularly larger, definitely dominant fish to act as boss and keep everyone else in line-- sometimes that helps and the boss or 'police' fish keeps the other fish on good behavior. This isn't fool-proof, since some may just ignore the other fish and let them squabble. The tank being open with everyone constantly in view of each other isn't helping. Not telling you to change the tank, but sometimes the dynamic changes when a tank is more broken up with driftwood, plants, dither fish, or simply more fish in the tank.
A lot of "sometimes." Different individual fish, different mixes of fish, and different tank situations all mean results can vary. What happens with one fish, group, or tank isn't always a foolproof rule.