The relationship dynamic/circumstantial conundrums
The hoarded space creates a tension with the outside world. Since truth can't get out, all household members are forced to live a false life to protect the truth from being used to shame and humiliate them. This makes the family a closed system - that not only cooperate more internally but also distances themselves from others, by extension.
Family members become like spies and they have to tip toe around the hoarder and his objects but they also have to be on their toes with any outsider that might be on to the truth.
It's very common that the hoard will start to poison every interaction any family member has. The moment they interact with someone new they are always split between humiliating the hoarder (and themselves by extension) or blindsiding this new person. This essentially tampers the relationship from the get go, dooming it for failure.
People pick up on the strange behavior. Some may even disregard it even if they knew the truth but the truth is sturdy and it changes the possibilities. In such a chaotic place you can't have family dinners, parties, group study sessions or invite people for professional reasons. It's crippling and it's an assault on family members. It's incredibly disrespectful and selfish.
If this charade goes on, soon the family members will start experiencing stress, paranoia and dissociation. A change in their conscious experience is very hard to crystalize because it requires an objective mind with sufficient perspective; which is exactly the opposite of what a person exposed to the hoard will start experiencing.
As a disclaimer, I have to affirm directly that the hoard and the hoarder are toxic, pathological and predatory. They know what they are doing.
It's even possible that the hoard started from slacking off, but soon enough it becomes a choice and they will leverage against the family members.
An important thing to remember when analyzing hoarders' behavior is to become comfortable with the fact that they act deliberately or accidentally in different aspects. This contradiction stems from their cognitive dissonance and constant hot and cold presentation of behaviors, moods and intentions. This means that a measured person needs to not fall into the trap of vilifying hoarders without 'giving the devil his due'. Because you have work with their own experience of themselves. And if they feel villified unjustly they will oppose you without compromise. But if you give them some leeway and even understanding you can prime them much better to accept where they are in the wrong.
Most people will tell you to ghost them or punish them - essentially opposing them - but in my experience, if you intend to deal with them on a regular basis, that is a mistake. You'll only raise animosity, create a scorched earth environment and make your own life a living hell. The correct way is to work with them and making compromises on both ends. You have to turn them into allies and show how they are implicated and affected by your own downfall.
As I've mentioned in different sections of this website, if you can leave and move on that may be a better choice; but if you can't, then you have to become a counselor, advisor and friend. You have to learn how to maneuver their emotions and guide them without creating big waves. Rage will make them uncooperative and resentful, and depression will make them ineffective and stalling.
You must realize that no one becomes a hoarder because their life is great. Hoarding is a coping mechanism like any other addiction or compulsion. They do it because it either makes their lives better or, more likely, because it doesn't make their life worse. This means that they are human. For good and for bad. And they may need love more than most. And punishment (negative reinforcement) doesn't compare with reward-giving as positive reinforcement to course-correct behavior.
Hoarders rationalize that if they can do it, then you can do it. In fact, they rationalize they are superior for doing so. That's how they solve the cognitive dissonance of being imposing and suffocating, disrespecting your boundaries, freedom and individual sovereignty.
Once the hoarder is on to the fact that a person is against their hoarding behaviors that they are willing to throw them away [behind their back] they become extremely paranoid and start supervising everything you do.
I once told my hoarder parent that one way to learn about people's behavior was to check their trashcan - something I've learned from the tv series 'HOUSE M.D.' - and she started clearing my trash from that point onwards. I did as bait to see if she would and she still clears my trash to this day, even when it's barely filled.
Notice how extremely invasive, controlling and surveillant this is. Even when my hoarder parent saw me put the trash out she often went there to check it out. She also often brought items back from the public trash.
Building trust is essential. At some point, to deal with a hoarder, you must acknowledge their feelings as legitimate, or at least their reality. You can't reason them away.
Being on their side means that you take into consideration their preoccupations. In my case, I went through a substantial part of the hoard and initially against their will. I took control of my environment because it was not only past the point of what's reasonable (well past), it was a life or death situation. The hoard will swallow you. Everything will swirl around the hoard and the hoarder; and it will subsume anyone in that environment to its designs. The hoard is a tyrannical space that subjects everyone to that 'social game' alone
In order to tone down the paranoia, and the mind games that ensue in that untrustworthy space, there must be mutual agreements and as well as mutual compromises. You must lay out the reality openly. No more games, no more hidden information or motives; and it's time to present your position and your destination; and work with them for both of your interests.
The hoarder is a person: people have fears, but they also have humanity. All actions are always positive or negative, with an effect on the moment; but actions all carry a symbolic 'grand' impact. When you introduce new negative actions, on a more extreme end, you are changing the rules of the game to make that 'fair game'. But you can also rule by decree, openly, that this type of action can't be made and is toxic on both ends.
This openness builds trust. You both acquiesce to your humanity: your fragility and your ability for cunning. And you both compromise for the better good.
One of the best ways to show you are on their side is to select objects you yourself acquiesce they will be interested in, but don't just select junk, select objects worth having. See, I don't advocate making their tendencies stop - it's unlikely they'll ever stop; they have a hole inside them they'll never truly fill. What I do advocate is to reroute their impetus and as time goes on you taper it down towards selective tastes and projects. The point is to guide them towards tangible action.
If there is something I have learned, for my own mental health and spiritual enlightenment, is that you have to see other people as if they were you from another perspective. This will give you enough empathy and perspective as a starting point to understand their motives, struggle and mental blocks.
By making things clear and overt, it makes actions on either end be seen for what they are: sabotage. The hoarder can no longer with a straight face not admit to what they're doing. If they still lie to their face, then there is no other solution but to leave that environment at any cost, because it's literally a deliberately deadly environment, and it becomes hopeless to expect to rehabilitate a person that wants to destroy you slowly.
Something that is worth mentioning is that, just like in narcissism, the dynamic is a zero-sum game - where one party is sacrificed at the expense of the other. The hoard is too limiting of possibilities to benefit anyone apart from the hoarder (which is unlikely to profit much as we've seen by the negative experience and outcomes the hoarder faces).