Notables __can__ change who they support, but it's pretty rare that it happens. If a notable is not currently supporting a clan, then it goes down the list of all clans with which they have > 50 relations. For each of these clans there is an RNG roll that happens once per day. The roll is a decimal between 0 and 1 and must be less than the result of the following equation to succeed:

**(relation - 50) / 2000**

Even if you have 100 relations with a notable, it still only gives you a 2.5% chance per day that they will support you.

Notables will flat out stop supporting a clan if they fall below 0 relations with them. When they are < 25 relations with their currently supported clan they have a chance to stop supporting the clan based on the equation:

**(25 - relation) / 500**

So for instance, if the clan has a relation of 24, then they only have a 0.2% chance of losing the notables support per day (5% at 0 relations). Technically, the player **does** have a low chance of gaining the support of a notable with the mechanic as currently implemented, but it's very rare.

I think all of the notable related stuff is still a work in progress, so I wouldn't expect things to remain as they are permanently.