The working magical-initiatory question of the day is, "How does one manage the emotionally awful energy being brought by others into one's sphere of sensation?"The basic solution: banish (or ground and center, depending on tradition).
The basic problem: banishing works just fine unless you have to live with this person (or even next-door) and s/he has become a dark star of continual misery. Banishing takes a bit of effort on your part while the walking toxic waste dump in the other room fouls the energetic environment almost effortlessly.
It's because that person hasn't attended to emotional-spiritual health that they've become a problem. So you have to act and they just have to be themselves. Even if you have a daily practice of spiritual hygiene, some of their waste product is going to seep across your boundaries. There aren't enough pentagram rituals and sage bundles in the world to keep it all away if you have to live with them (or, worse, interact with them regularly).
The intermediate solution: set up wards. Even if you're renting a room, you can do this. That plus daily banishing will be more effective. The nasty bits that get in when your energetic boundaries fade will hit the wards. If you give the wards a physical basis, all the better. They will last longer.
The intermediate problem: wards, like air filters, can only collect so much miasma before they stop functioning and become part of the problem. You have to renew / replace them regularly. They can go for a long time in normal circumstances. But if you're forced to exist in close proximity to a horrible, toxic individual, you're not in a "normal" circumstance. I'd attend to my wards at least once a week in that case. And wards plus daily banishing are still not a comprehensive fix.
The advanced solution: binding ritual. Psychologically unstable people, those who are inwardly broken or stunted, unreasonably angry people, idiots, parasites who are toxically needy and full of drama, and people being operated remotely by some kind of addiction or other malign influence can sometimes get through all of the above measures. They need to vent, to expel their toxins on someone else and draw good energy in. Intuitively feeling this, they will sometimes wade through all boundaries and protections in their miserable need to find relief, even if you've made it unpleasant for them. These people must be dealt with severely. They have no regard for your inner coherence, serenity, or health. They must be bound.
The advanced problem: bindings are temporary and can precipitate even more irrational and desperate behavior. If a person has no outlet for their wretchedness, it can spill out as physical violence directed at themselves or those around them. The only solution—maybe the best solution—is to physically remove yourself from their presence. This is sometimes far easier said than done.