The Mercere chapter of HoH:TL introduces the notion of "Heroic V&Fs. We read (p.104)
"Only “Heroic” characters can take Heroic Virtues and Flaws. These are characters with the Blood of Heroes virtue or the Legacy flaw, or magi with Mythic Blood. Other story circumstances such as Latent Magic Ability might warrant taking them, at the storyguide’s discretion."
What other "sources of heroism" do you allow in your games? I think, for example, that Major Magian Lineage would qualify. And there's a player in my troupe who is asking if Leper Magus (HoH:S) should qualify, since it provides a "major mystical lineage", like Mythic Blood or Legacy -- any opinions?
In my mind, the Cult of Heroes is House Mercere's attempt to compensate the proportion of mundanes in its House by attempting to breed / train / raise extra special mundanes, a number of which are redcaps. I wouldn't allow magi from other Houses to qualify short of being invited in a mystery cult, but this may not be strictly RAW.
I can not remember where off the top of my head, but there are in at least two other books which provide a base from which Heroic Virtues can be taken. I will have to dig around and see if I can find them.
HoH:S p. 106~107 has a basic blurb about Mystic Companions. They are actually open to any hedge magic tradition.
RoP:M p. 37 specifically states that Humans with a Might score can take Heroic Virtues/Flaws. They are also listed as common Virtues/Flaws for Beast of Virtue on p. 55.
While not one of the ones I was originally remembering, Fertility Magic has the option, at the Storyguide's discretion, of instilling some Heroic Virtues and Flaws.
The Clesrada, from The Contested Isle, is technically a Cult of Heroes. However it was originally taught by a faerie and they initiate Grogs & Companions into Heroic Virtues.
Jinn can possess Heroic Virtues and serve as a potential source of them.
Faerie Blood, if taken from one of the Heroic Lineages (Faerie Gods, such as descended from one of the Greek or Roman ones), can serve as a means of qualifying for Heroic Virtues with SG approval.
I know I am missing at least one other... my head is going to explode since it is not one that can be found with a search and so requires skimming through everything hoping to find it.
