I would actually think the "stronghold" would depend on whether or not you side with the cult of the absolute or with whatever other factions end up being available. They established a plot point of a Baldur's Gate VIP being kidnapped and in need of rescue, so depending on how that quest line gets completed (return him/her to Baldur's Gate safely, hand him over to Zhentarim or someone for ransom, or help the cult of the absolute return a doppleganger or tadpoled version of the VIP could all potentially result in your getting some sort of stronghold.
