@Kamran Rahman I have a 7 bed house and "house hack" with 6 other roommates. I've been doing this for 7 months now and have had to deal with many issues revolving around roommates getting along.
My house is setup perfectly for a house hack as there is no living room and not much space for people to bring friends over. However, I have had to deal with unwanted guests numerous times.
One thing I'd recommend is to have them both sit down with you one night and have a talk about everything. Lay it all out on the line. Let roommate one voice their concerns and allow roommate two to hear them and see how they react.
When you run a house hack, you need to be the alpha of the house. The leader. This isn't talked about anywhere on Bigger Pockets. Both of these roommates are looking at you to provide them with an enjoyable living arrangement. It's on you to provide this for them.
So now it's on you to solve this problem. I would highly recommend having them talk it out with you there. Proceed accordingly.
@James Galla mentions a very important point with house hacking. In the future, you really have to screen people not only for their ability to pay, but also their ability to fit in to your house hack. I know nothing more about the eccentric roommate, but if I'm reading this correctly, he sounds like a problem.
Roommate one is probably upset because there are 4 people in the house, instead of the expected 3. I don't deal well with noise so another roommate playing loud tv noise would be upsetting to me. Additionally, it sounds like roommate 1 is uncomfortable with a random guest hanging out in the living room all the time. This is a valid complaint. Without further info, I'm going to assume that there are times where this guest is there without roommate 2. That's an uncomfortable feeling for roommate 1 if they need to leave and they're worrying about their stuff getting taken.
I have a house rules document that I give to everyone who moves in. I make it very clear what I expect of roommates. If they don't follow the rules, then they will be asked to leave. You may need to start enforcing rules to ensure all roommates are comfortable living there.