The 4th house is the deepest house, it indicates the connection with the family, with the family, with the roots. And if there are constant clarifications of relationships, quarrels in the family of such a person, they experience strong stress. In their home, they dream of finding peace, and there is no place for storms here.
A person with Neptune in the 4th house has increased intuition and sensitivity in their relationships with relatives. They perfectly feel their mood, experiences.
They have a strong subconscious connection with the family, with the parents, with the family and with the Motherland in general. They are attached to their ancestors, since Neptune in astrology personifies grandmothers, grandfathers, and is also associated with the theme of blood and ancestral karma - therefore, the ancestral theme sounds good in the 4th house. With such a position of Neptune, the person is unlikely to want to emigrate, since they are attached to their place by their roots. This does not mean that the person will live their whole life at one address, they just love their Motherland very much. Yes, they may travel, may admire other cultures, but away from their Motherland, from their home, they will begin to miss. And wherever they are, they are always drawn home.
Relationships with parents are quite emotional. Both for better and for worse. They can be very close, soulful. Parents can be quite soft (here we must necessarily take into account the Moon as the image of the mother, and the Sun with Saturn as the signifiers of the father), the person may idealize them. Or it may indicate problems with parents, for example, alcoholism, or Neptune gives a secret of origin, or there are some secrets in the family that are hidden from the person. The person may not know their biological father, or the child was adopted. There may be other "skeletons in the closet" or secrets of the family that will eventually be revealed to the owner of such Neptune.
The ancestors themselves can be "Neptunian". An example from life - the grandfather deceived, robbed, abandoned his family, and the grandmother was gullible all her life: she fell in love and was repeatedly disappointed. This is a negative example. On the positive side, a person can inherit from their ancestors abilities in the field of Neptune: clairvoyance, strong intuition, divination or creative abilities. There may be priests, healers, herbalists, sorcerers, etc. in the family.
In the house, there are very often situations related to water - problems with water supply or some leaks: the person themselves can flood the neighbors downstairs, or they are flooded by the neighbors. It is ideal for a person to live near water. And they really strive for this: either a house near a reservoir, a lake, a river, or if they cannot afford such housing, the person keeps an aquarium. And for the person, it is really very important to be in this relaxing moment in their home: they look at the water and calm down, recharge - this is meditation.
The person may have confusing and complex stories with real estate: the apartment may be registered in someone else's name, or they are the owner, but for some reason cannot use it.