In the CAO Times ephemeris the keywords for this body are: "fixation, intensity, crisis-mastery, exaltation, commitment, challenge." It also says: "The liabilities---especially with conjunctions---are tunnel vision, blind spots, irrational awe, imbalance, obsession." These keys seem to be quite valid, especially the second part.
In a relationship, if one person's Apollo is conjunct the Sun, Moon, Venus, Mars or Ascendant of the other person, the love the Apollo person receives is unbelievable. It is sometimes to the point of worship. This can be especially true in a parent-child relationship. A case in point: a woman does not really like children and barely tolerates her own. However when she has her third child, the baby has Apollo exactly on the woman's Virgo Moon. The mother adores the child, loves it, and cannot believe that she can feel so strongly toward the child.
On the negative side, in a long-term relationship the planet person may grow weary of worshipping the Apollo person, and begin to resent some of the very qualities he once idolized. As you might imagine, in the above example, the mother found herself regretting the way she had spoiled this child, once he reached adolescence!
By house it seems to denote a place where you feel that it is your right to expect your own way, and often where you take for granted some particular personal rights you have always respected. If these are transgressed you can be totally dumbfounded, unable to believe that such a thing has occurred. And you may not have any idea how to rectify the situation.