I´m thinking about a character, that learns Summoning as described in "The Infernal", p. 114 - 115 (Ars Goetia). It is an NPC and he should learn the ability while the saga is in progress. He doesn´t have The Gift. It is acceptable for him that the use of his new ability counts as tainted and will be perceived as unholy by Divine Powers of investigation (see insert: The Infernal, p. 115) but at its heart the character is not an infernal one. His Summoning Ability will be associated with the Magic Realm.
My question is: How can he learn this ability?
In RAW, p. 166 there are rules about "Learning Supernatural Abilities", but they are only valid for characters with The Gift. "The Infernal", p. 126, states: "Any companion characters or magi who have somehow been touched by evil can learn Supernatural Abilities associated with the Infernal realm [...] This study activity follows the same rules as for magi learning magical Supernatural Abilities [...]" Later, some Infernal Traditions are described. Some of them use Summoning as "Favored Abilities".
My ungifted character isn´t "touched by evil". He only wants to learn [Magic] Summoning. Is it possible for him to learn "Summoning" following the rules as for magi learning magical Supernatural Abilities? Or does he need a mystery initiation? (I´d like to avoid that). Or is there another way?