elockanllor said:
It has a prereq of "familiar within 5 feet". Other feats have prereqs like "dex 13+" and the like. What is the difference? All this talk of conditional feats is entirely external from the PHB.
Now we get to the heart of the matter.
"Within 5 feet" is not a prerequisite.
It is a condition.
The definition of a prerequisite is that you have to satisfy the prerequisite in order to acquire a feat.
In the case of Alertness and Familiars though, you do not acquire a feat. You take a character class which gives you the option of the familiar which in turn gives you the conditional option of gaining the feat.
And, you do not choose Alertness from a list of feats, you get it by default due to taking a given class.
This is no different than any other virtual feat IMO. It is a feat or feat-like ability acquired not by acquiring a feat out of a choice of feats, but by taking a class which gives you this one set ability or feat.
Btw, I agree with your POV with regard to whether you should allow the Alertness feat to be a prerequisite. I've said that several times in this thread.
But, I disagree that Alertness gained this way is a normal feat. If I was a DM who did not allow virtual feats to be used (which powers up the game as LokiDR has mentioned), then I would not allow Alertness from a familiar to be used this way.
And, the real crux of the issue here for me is not which feats are virtual and which are not, the real issue for me is the "losing a prerequisite loses the ability" issue.
Not only will poison drop the Dex of a Fighter, it will make him lose the use of all of the feats anywhere above a Dex based chain (PHB pg. 77). Plus, he will lose all PrC special abilities if the PrC had a prerequisite of any of those feats (DMG pg. 27).
This to me is a very short sighted set of rules. IMO. You basically get double whammied in that not only are your missile weapons, your Reflex saves, and your AC at a minus (typically, even if you are wearing full plate), but you also lose a bunch of feats and special abilities.
For example, alignment. The loss of an alignment prerequisite for a PrC should mean that you are not inclined to use those PrC abilities, but you still have the ability to do it if you need to (which might send you back to that alignment if you do). It should not be that now that I am Neutral and no longer Evil, I no longer can assassinate anyone. I should just be disinclined to assassinate anyone.