At the end of Canto 7 of Limbus Company, we get to witness the first meeting between two people: Don Quixote, a bloodfiend (aka a vampire), and Sancho, a depressed suicidal woman. Donqui asks Sancho something along the lines of: Why do you seek death? To free you from suffering? I thought humans transferred that suffering to others to feel better. To which Sancho more or less responds with: that's stupid as fuck, making others suffer like I do will do nothing to ease my own suffering.
Now that is an important exchange for many reasons, but the bit I wanna focus on rn is that... well, "inflicting my suffering upon others in the hope that it will lessens my own" is more or less what Donqui is doing.
Some context: according to Sanson earlier in the Canto, the reason why Donqui is turning other folks into bloodfiends is so he would feel less lonely with a family by his side. It is also very strongly implied that being a bloodfiend comes with an inherent sense of loneliness and a debilitating thirst for blood, and both these things are equivalent (Sancho & Donqui manage to go without blood for a fairly long time as people who have formed an actual emotional bond, while everyone else surviving off blood substitute is slowly going insane because the issue has never been the blood, but rather the isolation that comes with being a vampire). So: Donqui's way of battling loneliness IS essentially to force other people to suffer like he does, and then traumabond over that.
And as Sancho stated earlier: it's stupid and it doesn't work. Sure, suffering from bloodthirst together makes for a common ground, but it's very clear as the story goes that this is the only thing Donqui's vampire crew has in common. Multiple bloodfiends seem convinced that Sancho hates them or doesn't remember them, implying that for all they call themselves "family" their interpersonal relationships aren't all that great. Hell, Donqui's bloodfiends love him, but they also can't go against him (quite literally) so they usually nod and go along with whatever he suggests instead of debating with him and having meaningful conversations with him. Everbody loves Don Quixote. No one knows Don Quixote.
The end result is that all these people are extremely lonely, and they're spreading that loneliness like a disease in a vague attempt to feel better, like whales creating mermaids. Which does not work. Because vampires generally inherently have a hierarchy between them (see the whole "cannot go against Donqui" bit) meaning it is impossible for anyone here to form a genuine connection as equals.
The one thing that worked for Sancho was finding people who were completely outside of the whole vampire shit, meaning people she can actually bond with as equals. Not parents or children or siblings forced to get along with you, not yes-man or enablers or any blind fan who couldn't tell her shit. Actual friends who can call her out when she fucks up and have actual discussions with her and love her for reasons others than filial piety. A blessed family of twelve, that can alleviate her loneliness and her bloodthirst.